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Abstract:

A conveyor oven according to some embodiments has a first mode and a
second mode of operation and includes a tunnel in which food is cooked, a
conveyor for moving the food through the tunnel, a first set and a second
set of one or more burners, each set configured to generate heat for the
tunnel, and a controller responsive to the detection of an absence of
food in the tunnel, the controller configured to change operation of the
first set of one or more burners and the second set of one or more
burners from the first mode of operation to the second mode of operation
based at least in part upon the detection of the absence of food product
from the tunnel.

Claims:

1. A conveyor oven having a first mode and a second mode of operation,
the conveyor oven comprising: a tunnel in which food is cooked; a
conveyor moveable to convey the food through the tunnel; a first set of
one or more burners configured to generate heat for the tunnel, wherein
the first set of one or more burners is operable at a first output during
the first mode of operation and is variable to a different output in the
second mode of operation; a second set of one or more burners configured
to generate heat for the tunnel, the second set of one or more burners
operating at a first output during the first mode of operation and is
turned off in the second mode of operation; and a controller responsive
to the detection of the absence of food in the tunnel, the controller
configured to change operation of the first set of one or more burners
and the second set of one or more burners from the first mode of
operation to the second mode of operation based at least in part upon the
detection of the absence of food product from the tunnel.

2. The conveyor oven of claim 1, further comprising a fan to circulate
air within the tunnel, wherein the speed of the fan is variable between
the first mode of operation and the second mode of operation.

3. The conveyor oven of claim 2, wherein the speed of the fan in the
second mode of operation is less than the speed of the fan in the first
mode of operation.

4. The conveyor oven of claim 1, further comprising a first valve to
regulate flow of gas to the first set of one or more burners and a second
valve to regulate flow of gas to the second set of one or more burners.

5. The conveyor oven of claim 1, wherein the controller changes operation
of the first set of one or more burners and the second set of one or more
burners between the first mode of operation and the second mode of
operation based upon passage of a predetermined period of time indicating
the absence of food in the tunnel.

6. The conveyor oven of claim 1, wherein the controller adjusts the
output of the first set of one or more burners in the second mode of
operation in response to a change in temperature of the oven to maintain
the oven substantially at a steady state temperature.

7. The conveyor oven of claim 6, wherein the change in temperature of the
oven is due at least in part to the absence of food from the tunnel.

8. The conveyor oven of claim 6, wherein the steady state temperature is
a cooking temperature.

9. A conveyor oven having a first mode and a second mode of operation,
the conveyor oven comprising: a tunnel in which food is cooked; a
conveyor moveable to convey the food through the tunnel; a first set of
one or more burners configured to generate heat for the tunnel; a first
valve configured to regulate the flow of gas to the first set of one or
more burners, where gas flows through the first valve at a first flow
rate during the first mode of operation and is variable to a different
flow rate during the second mode of operation, wherein the first valve
allows at least some gas to flow therethrough at the different flow rate;
a second set of one or more burners configured to generate heat for the
tunnel; a second valve configured to regulate the flow of gas to the
second set of one or more burners, where gas flows through the second
valve at a first flow rate during the first mode of operation and is
prevented from flowing therethrough during the second mode of operation;
and a controller responsive to a signal associated with an absence of
food in the tunnel, wherein the controller adjusts the first valve and
the second valve between the first mode of operation and the second mode
of operation based at least in part upon the signal.

10. The conveyor oven of claim 9, further comprising a fan for
circulating air within the tunnel, wherein the speed of the fan is
adjustable between the first mode of operation and the second mode of
operation.

11. The conveyor oven of claim 10, wherein the speed of the fan in the
second mode of operation is less than the speed of the fan in the first
mode of operation.

12. The conveyor oven of claim 9, wherein the controller changes
operation of the first set of one or more burners and the second set of
one or more burners between the first mode of operation and the second
mode of operation based upon passage of a predetermined period of time
indicating the absence of food in the tunnel.

13. The conveyor oven of claim 9, wherein the controller adjusts the
output of the first set of one or more burners in the second mode of
operation in response to a change in temperature of the oven to maintain
the oven substantially at a steady state temperature.

14. The conveyor oven of claim 13, wherein the change in temperature of
the oven is due at least in part to the absence of food from the tunnel.

15. The conveyor oven of claim 13, wherein the steady state temperature
is a cooking temperature.

16. A conveyor oven for cooking food product having a first and second
mode of operation, the conveyor oven comprising: a tunnel in which food
is cooked; a conveyor for moving the food through the tunnel; a heat
source operable to generate heat to be provided to the tunnel, wherein
the heat source comprises a first set of one or more burners and a second
set of one or more burners; a fan operable to move air in the tunnel; and
at least one controller that controls at least one of the fan and the
heat source, and is responsive to the detection of the absence of food
from the tunnel to change the oven from the first mode of operation to
the second mode of operation, wherein in the second mode of operation (i)
the fan moves air in the tunnel at a speed that is reduced from the speed
of the fan when the oven was in the first mode of operation, (ii) the
output of the first set of one or more burners is adjusted in response to
a change in temperature in the oven to maintain the oven substantially at
a steady state temperature, and (iii) the second set of burners is turned
off.

17. The conveyor oven of claim 16, further comprising an input device
that transmits information indicating food product is to be cooked.

18. The conveyor oven of claim 16, further comprising a first valve to
regulate flow of gas to the first set of one or more burners and a second
valve to regulate flow of gas to the second set of one or more burners.

19. The conveyor oven of claim 16, wherein the controller changes
operation of the first set of one or more burners and the second set of
one or more burners between the first mode of operation and the second
mode of operation based upon passage of a predetermined period of time
indicating the absence of food in the tunnel.

20. The conveyor oven of claim 16, wherein the change in temperature of
the oven is due at least in part to the absence of food from the tunnel.

21. The conveyor oven of claim 16, wherein the steady state temperature
is a cooking temperature.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and is a Continuation of U.S.
patent application Ser. No. 12/233,969, filed Sep. 19, 2008, which is a
Continuation of U.S. patent application Ser. No. 11/526,133, filed Sep.
22, 2006, which is a Continuation of International Patent Application No.
PCT/US2006/022304, filed Jun. 8, 2006. U.S. patent application Ser. No.
11/526,133 is also a Continuation-in-part of International Patent
Application No. PCT/US2005/038783, filed Oct. 27, 2005, and is also a
Continuation-in-part of International Patent Application No.
PCT/US2005/009546, filed Mar. 23, 2005, which claims the benefit of U.S.
Provisional Patent Application No. 60/555,474, filed Mar. 23, 2004.

[0002] U.S. patent application Ser. No. 12/233,969 published as U.S.
Publication No. 2009/0075224 on Mar. 19, 2009; U.S. patent application
Ser. No. 11/526,133 issued as U.S. Pat. No. 8,087,407 on Jan. 3, 2012;
International Patent Application No. PCT/US2006/022304 published as
International Publication No. WO 2007/050136 on May 3, 2007;
International Patent Application No. PCT/US2005/038783 published as
International Publication No. WO 2006/101531 on Sep. 28, 2006;
International Patent Application No. PCT/US2005/009546 published as
International Publication No. WO 2005/094647 on Oct. 13, 2005; and U.S.
Provisional Patent Application No. 60/555,474 was filed Mar. 23, 2004.
The entire contents of each of the foregoing applications and
publications are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0003] A conveyor oven is an oven with a conveyor that moves through a
heated tunnel in the oven. Conveyor ovens are widely used for baking food
products, especially pizzas, and the like. Examples of such ovens are
shown, for example, in U.S. Pat. Nos. 5,277,105, 6,481,433 and 6,655,373.

[0004] Conveyor ovens are typically large metallic housings with a heated
tunnel extending through them and a conveyor running through the tunnel.
Usually such conveyor ovens are either 70 inches or 55 inches long,
although they may be constructed in any suitable size. The conveyor
transports food products through the heated oven tunnel at a speed which
bakes food products during their transit through the tunnel. The conveyor
ovens include a heat delivery system including blowers which supply heat
to the tunnel from a plenum through passageways leading to metal fingers
opening into the oven tunnel, at locations above and below the conveyor.
The metal fingers act as airflow channels that deliver streams of hot air
which impinge upon the surfaces of the food products passing through the
tunnel on the conveyor. In modern conveyor ovens, a microprocessor-driven
control panel generally enables the user to regulate the heat, the speed
of the conveyor, etc., to properly bake the food product being
transported through the oven.

[0005] The conveyor generally travels at a speed calculated to properly
bake food products on the belt during the time period required for the
conveyor to carry them through the entire length of the oven tunnel.
Other food products requiring less time to bake may be placed on the
conveyor at a point part way through the oven so that they travel only a
portion of the length of the tunnel. A pizza is an example of a product
which might require the full amount of baking time in order to be
completely baked in the oven. A sandwich is an example of a product which
might require only a portion of the full baking time.

[0006] Conveyor ovens are typically used in restaurant kitchens and
commercial food manufacturing facilities. Typically they are kept running
for extended periods of time, including periods when products are not
being baked. Since the inlet and outlet ends of the oven are open, this
means that heat and noise are continuously escaping from the conveyor
oven tunnel into the surrounding environment. This escape of heat wastes
energy. It also warms the surrounding environment, usually unnecessarily
and often to uncomfortable levels. This is particularly the case where
the conveyor oven is being used in relatively cramped restaurant kitchen
environments. The escaping noise is also undesirable since it may
interfere with interpersonal communication among those working near the
oven.

[0007] Conventional conveyor ovens also provide users with limited ability
to reduce energy losses while running at less than full capacity.
Typically, users only have the ability to turn such ovens on or off,
which in many cases involves an unacceptably long shut-down and/or
start-up times. Therefore, it is necessary to leave such ovens on despite
the waste of fuel or other energy supplied to the ovens when cooking food
intermittently. It is not uncommon for a conventional conveyor oven to be
left running in a full production mode for substantially the entire
period of time a restaurant or other cooking facility is open.

[0008] It is generally desirable to maintain uniform heating from one end
of the heated tunnel of the oven to the other. Among the challenges to be
overcome in achieving such uniform heating are the inherent variations in
heating from oven to oven due to variations in the internal physical
environment of otherwise identical ovens. A more significant challenge to
maintaining uniform heating through the length of the heated tunnel is
the constantly changing physical and thermal configuration of the tunnel
as food products being baked pass from one end of the tunnel to the
other. For example, raw pizzas entering the inlet to the tunnel
constantly change the physical and thermal configuration of the tunnel
environment as they advance to the other end while drawing and emitting
ever-varying amounts of heat. As a result, temperatures can vary by as
much as 50-60° F. from one end of the tunnel to the other.

[0009] Currently, the most common technique for balancing the heating
through the length of the tunnel involves monitoring temperatures near
the inlet and outlet ends of the heated tunnel to maintain a
predetermined average temperature over the length of the tunnel. Thus,
for example, as a cold raw pizza enters the inlet to the tunnel causing a
sudden drop in the tunnel temperature at the inlet, the drop in
temperature is sensed and more heat is supplied to the tunnel to raise
the temperature near the inlet heat sensor. Unfortunately, this also
raises the temperature at the outlet of the oven, which causes the heat
sensor at the outlet to trigger a heating reduction to prevent an
excessive temperature at the oven outlet. In this way, temperature
sensors near the inlet and outlet of the oven help to balance the heating
of the tunnel to generally maintain a target average temperature.

[0010] However, uniform heating through the length of the heated tunnel
cannot be achieved in this way. Thus, food products traveling through the
oven do not see uniform heating which, it has been discovered, makes it
necessary to slow the conveyor to a speed which completes the baking in
more time than would be the case if uniform heating could be achieved
throughout the length of the heated tunnel. In other words, improved
heating uniformity from one end of the tunnel to the other may reduce
required baking times.

[0011] Additionally, in many applications it is necessary to be able to
operate the conveyor oven using either side as the inlet, by running the
conveyor belt either from left-to-right for a left side inlet, or from
right-to-left for a right side inlet. To be most successful in such
interchangeable applications, it is particularly desirable to produce a
uniform temperature from one end of the heated tunnel to the other.

BRIEF SUMMARY OF THE INVENTION

[0012] Some embodiments of the present invention provide a conveyor oven
having a first mode and a second mode of operation, the conveyor oven
comprising a tunnel in which food is cooked; a conveyor moveable to
convey the food through the tunnel; a first set of one or more burners
configured to generate heat for the tunnel, wherein the first set of one
or more burners is operable at a first output during the first mode of
operation and is variable to a different output in the second mode of
operation; a second set of one or more burners configured to generate
heat for the tunnel, the second set of one or more burners operating at a
first output during the first mode of operation and is turned off in the
second mode of operation; and a controller responsive to the detection of
the absence of food in the tunnel, the controller configured to change
operation of the first set of one or more burners and the second set of
one or more burners from the first mode of operation to the second mode
of operation based at least in part upon the detection of the absence of
food product from the tunnel.

[0013] In some embodiments, a conveyor oven having a first mode and a
second mode of operation is provided, and comprises a tunnel in which
food is cooked; a conveyor moveable to convey the food through the
tunnel; a first set of one or more burners configured to generate heat
for the tunnel; a first valve configured to regulate the flow of gas to
the first set of one or more burners, where gas flows through the first
valve at a first flow rate during the first mode of operation and is
variable to a different flow rate during the second mode of operation,
wherein the first valve allows at least some gas to flow therethrough at
the different flow rate; a second set of one or more burners configured
to generate heat for the tunnel; a second valve configured to regulate
the flow of gas to the second set of one or more burners, where gas flows
through the second valve at a first flow rate during the first mode of
operation and is prevented from flowing therethrough during the second
mode of operation; and a controller responsive to a signal associated
with an absence of food in the tunnel, wherein the controller adjusts the
first valve and the second valve between the first mode of operation and
the second mode of operation based at least in part upon the signal.

[0014] Some embodiments of the present invention provide a conveyor oven
for cooking food product having a first and second mode of operation,
wherein the conveyor oven comprises a tunnel in which food is cooked; a
conveyor for moving the food through the tunnel; a heat source operable
to generate heat to be provided to the tunnel, wherein the heat source
comprises a first set of one or more burners and a second set of one or
more burners; a fan operable to move air in the tunnel; and at least one
controller that controls at least one of the fan and the heat source, and
is responsive to the detection of the absence of food from the tunnel to
change the oven from the first mode of operation to the second mode of
operation, wherein in the second mode of operation (i) the fan moves air
in the tunnel at a speed that is reduced from the speed of the fan when
the oven was in the first mode of operation, (ii) the output of the first
set of one or more burners is adjusted in response to a change in
temperature in the oven to maintain the oven substantially at a steady
state temperature, and (iii) the second set of burners is turned off.

[0015] Further aspects of the present invention, together with the
organization and operation thereof, will become apparent from the
following detailed description of the invention when taken in conjunction
with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Preferred embodiments of the invention are shown in the attached
drawings, in which:

[0017] FIG. 1 is a perspective view of a conveyor oven in accordance with
an embodiment of the present invention;

[0018]FIG. 2 is a perspective view of a portion of the conveyor oven of
FIG. 1, in which a hinged oven access panel has been opened to reveal
some of the internal workings of the oven;

[0019]FIG. 3 is an enlarged elevation view of an embodiment of the
controls of the oven of FIG. 1;

[0020]FIG. 3A is a schematic illustration of an embodiment of the control
system of the conveyor oven of FIG. 1;

[0021]FIG. 4 is a diagrammatic representation of the tunnel of the oven
of FIG. 1, apportioned into two segments with independent temperature
sensing and independent heat delivery means;

[0022] FIGS. 5A-5C include a diagrammatic representation of a pizza moving
through the heated tunnel of the conveyor oven of FIG. 1, with graphs
showing changing BTU burner output and blower output as the pizza
advances through the tunnel;

[0023]FIG. 6 is a diagrammatic representation of a single burner of a
contiguous multiple burner configuration in accordance with an embodiment
of the present invention;

[0024]FIG. 6A illustrates a venturi support disk of the burner of FIG. 6;

[0025] FIG. 6B illustrates a flame retention member of the venturi tube of
the burner of FIG. 6;

[0026] FIGS. 7A and 7B are perspective views of a pair of contiguous
burners in accordance with an embodiment of the present invention;

[0027] FIG. 8 shows the distal ends of the outer tubes of the burners of
FIGS. 7A-7B;

[0029]FIG. 10 illustrates an alternative dual contiguous burner
configuration in accordance with an embodiment the present invention; and

[0030] FIG. 11 is a top plan view of selected elements of the oven of FIG.
1.

[0031] FIG. 12 is a flowchart illustrating an energy management mode for
the conveyor oven of FIG. 1.

[0032]FIG. 13 is a flowchart illustrating an energy management mode for
the conveyor oven of FIG. 1.

[0033]FIG. 14 is a flowchart illustrating an energy management mode for
the conveyor oven of FIG. 1.

[0034]FIG. 15 is a flowchart illustrating a combination of the energy
management modes illustrated in FIGS. 12 and 13 for the conveyor oven of
FIG. 1.

[0035]FIG. 16 is a flowchart illustrating a combination of the energy
management modes illustrated in FIGS. 12, 13, and 14 for the conveyor
oven of FIG. 1.

[0036]FIG. 17 is a schematic illustration of an alternative embodiment of
the control system of the conveyor oven of FIG. 1.

[0037]FIG. 18A illustrates an embodiment of a main screen of an operator
interface for the control system illustrated in FIG. 17.

[0038] FIG. 18B illustrates another embodiment of a main screen of an
operator interface for the control system illustrated in FIG. 17.

[0039] FIG. 19 illustrates an embodiment of a temperature setting screen
of an operator interface for the control system illustrated in FIG. 17.

[0040]FIG. 20 illustrates an embodiment of a temperature tuning screen of
an operator interface for the control system illustrated in FIG. 17.

[0041]FIG. 21A illustrates an embodiment of a belt tuning screen of an
operator interface for the control system illustrated in FIG. 17.

[0042] FIG. 21B illustrates another embodiment of a belt tuning screen of
an operator interface for the control system illustrated in FIG. 17.

[0043]FIG. 22 illustrates an embodiment of a belt set-up screen of an
operator interface for the control system illustrated in FIG. 17.

[0044] FIGS. 23A, 23B, and 23C illustrate an embodiment of energy savings
mode set-up screens of an operator interface for the control system
illustrated in FIG. 17.

[0045]FIG. 24 is an example of a food service floor plan showing a
controller for a conveyor oven connected to several remote devices.

[0046] FIGS. 25A and B are examples of time lines of conveyor oven
operation based on indications from one or more remote devices.

DETAILED DESCRIPTION

[0047] Before any embodiments of the invention are explained in detail, it
is to be understood that the invention is not limited in its application
to the details of construction and the arrangement of components set
forth in the following description or illustrated in the following
drawings. The invention is capable of other embodiments and of being
practiced or of being carried out in various ways. Also, it is to be
understood that the phraseology and terminology used herein is for the
purpose of description and should not be regarded as limiting. The use of
"including," "comprising," or "having" and variations thereof herein is
meant to encompass the items listed thereafter and equivalents thereof as
well as additional items. Unless limited otherwise, the terms
"connected," "coupled," and "mounted" and variations thereof herein are
used broadly and encompass direct and indirect connections, couplings,
and mountings, and the terms "connected" and "coupled" and variations
thereof are not restricted to physical or mechanical connections or
couplings. Also, it is to be understood that phraseology and terminology
used herein with reference to device or element orientation (such as, for
example, terms like "front", "back", "up", "down", "top", "bottom", and
the like) are only used to simplify description of the present invention,
and do not alone indicate or imply that the device or element referred to
must have a particular orientation. In addition, terms such as "first",
"second", and "third" are used herein and in the appended claims for
purposes of description and are not intended to indicate or imply
relative importance or significance.

Conveyors

[0048] FIG. 1 shows a conveyor oven 20 having a conveyor 22 which runs
through a heated tunnel 24 of the oven. The conveyor 22 has a width
generally corresponding to the width of the heated tunnel 24 and is
designed to travel in direction A from left oven end 26 toward right oven
end 28 or, alternatively in direction B, from right oven end 28 toward
left oven end 26. Thus, oven ends 26 and 28 may serve respectively as the
inlet and outlet of an oven with a rightwardly moving conveyor or as the
outlet and inlet of an oven with a leftwardly moving conveyor.

[0049] The support, tracking and drive of conveyor 22 are achieved using
conventional techniques such as those described in U.S. Pat. Nos.
5,277,105 and 6,481,433 and 6,655,373, the contents of which are
incorporated herein by reference insofar as they relate to conveyor
support, tracking, and drive systems and related methods. In the
illustrated embodiment, a chain link drive is housed within compartment
30 at the left end 26 of the oven. Thus, a food product, such as a raw
pizza 32R, may be placed on the conveyor 22 of the ingoing left oven end
26 and removed from the conveyor 22 as fully baked pizza 32C (see FIG.
5C) at the outgoing right oven end 28. The speed at which the conveyor 22
moves is coordinated with the temperature in the heated tunnel 24 so that
the emerging fully cooked pizza 32C is properly baked.

[0050] Normally only one conveyor is used, as shown. However, certain
specialized applications may make two or more conveyors a preferable
design. For example, a first conveyor may begin at left oven end 26 and
travel at one speed to the center or other location of the oven 20, while
a second conveyor beginning at such a location and ending at the right
oven end 28 may travel at a different speed. Alternatively, conveyors
that are split longitudinally may be used, so that one conveyor carries a
product in direction A while the other conveyor carries a product in
direction B, or so that two side-by-side conveyors carry product in
parallel paths and in the same direction (A or B) through the oven 20.
This enables one product to travel on the conveyor at one speed to bake
one kind of product and the other conveyor to travel on the other
conveyor at a different speed to bake another kind of product. In
addition, three or more side-by-side conveyors can carry product in
parallel paths through the oven 20.

Access

[0051] With reference to FIG. 1, a hinged door 34 is provided on the front
of the oven 20, with a heat resistant glass panel 36 and a handle 35 so
that a person operating the oven can view food product as it travels
through the oven 20. A stainless steel metal frame surrounds the oven
opening and provides a support for a gasket of suitable material (not
shown), so that when the door 34 is in its closed position, it fits
against and compresses the gasket to retain heat in the oven 20. Also,
the operator may open the door 34 by pulling on handle 35 to place a
different product on the conveyor 22 if less than a full bake cycle is
required to produce a fully cooked product.

[0052] A hinged oven access panel 38 is also provided, open as shown in
FIG. 2, to expose inner workings and controls of the oven 20. As
explained in more detail below, in some embodiments the hot air blowers
and ducts, their associated components, and/or the temperature sensors of
the oven 20 can be located within the area revealed by the opened access
panel 38.

Oven Controls

[0053]FIG. 3A shows a schematic illustration of the control system for
the oven 20. A microprocessor-based controller 42 may include a central
processing unit ("CPU") 650, one or more displays 655, and a control
interface 660. The CPU 650 can control a plurality of devices including
one or more burners 60, 62 (including one or more blower switches,
ignition switches and blowers, fuel valves, and flame sensing elements),
one or more fans 72, 74 (described in greater detail below), and one or
more conveyors 22. The CPU 650 may also receive input from a plurality of
sensors including one or more temperature sensors 80, 82 and one or more
photo sensors 79, 81 and/or 83, 85 (also described in greater detail
below).

[0054] The oven controls, as shown in FIG. 3B, can include the controller
42 (such as a Honeywell UDC 3300 controller) which may be programmed to
control and monitor the baking process by pressing appropriate set-up and
display buttons 44a-44h while viewing alphanumeric display 46, which will
display process variables and setpoints including oven temperature, hot
air blower speed, etc. A "heat on" indicator can be illuminated when a
minimum threshold heat output is generated by the oven 20 under control
of the controller 42. The present temperature and/or the programmed
setpoint temperature may be displayed. By simultaneously pressing
selected keys in some embodiments, the value of the heat output with the
heat on indicator in the "on" condition can be displayed. Also, the
controller 42 can be configured to enable a user to cycle through actual
temperature display indicators to reveal the actual temperatures,
setpoint temperature, and the heat on condition. In the illustrated
embodiment, the speed and direction of the conveyor 22 can be set using
buttons 48a, 48b, 50a and 50b and their associated displays 48c and 50c.

[0055] In some embodiments, the output display 46 can be automatically
locked in a default display when a service person or operator places the
controller 42 in a service mode by pressing appropriate key(s). Also, a
failsafe condition can occur when any one of various tests fail, at which
time a signal display (e.g., one or more flashing indicators) can be
displayed, such as a signal display flashing alternately with a
temperature display. For example, if the oven 20 has not reached
200° F. within 15 minutes after an initial power-up of the oven
20, a message can be flashed on the display panel 46 indicating that
controls need to be reset (e.g., power-cycled). As another example, if a
temperature sensor fails to operate properly, the display 46 can flash
"open". Also, the display 46 can provide one or more prompts for
servicing the oven 20. Each additional press of a service tool key can
advance so that a service person can continually sequence through service
prompts of a service mode. The service mode can be exited, for example,
by either pressing an appropriate key or by pressing no key for a set
period of time (e.g., sixty seconds). In either case, the system can be
automatically returned to a normal state.

[0056] In the illustrated embodiment, a setpoint lock key 42d can
automatically flash the temperature that has been selected for an
operation of the oven 20. In some embodiments, this setpoint temperature
can be increased or decreased by pressing either increment or decrement
keys 42f, 42g. Also, in some embodiments the degrees (° F. or
° C.) used for the prompts can be changed by pressing either the
increment or decrement keys 42f, 42g. While at a degrees ° F. or
° C. prompt, a selection of "F" or "C" can automatically change
the units of all the display 46 to ° F. or ° C. While a
default display prompt is being displayed, an indicator can flash to
indicate which display is chosen as the default display, which can be
changed, for example, by pressing either the increment or decrement keys
42f, 42g.

[0057] In some embodiments, the oven 20 is operated by: (1) turning a
blower control 52 to an "ON" position to start a blower (described in
greater detail below), (2) setting the temperature to a desired level
using the controller 42 as described above, (3) turning a heat control 54
to an "ON" position to supply gas and to trigger ignition of the oven
burner(s) (described in greater detail below), (4) turning a conveyor
control 56 to an "ON" position to drive the conveyor 22, and (5) after an
appropriate pre-heat period, placing food products on the conveyor and
beginning the baking process.

Tunnel Segments

[0058] Heat delivery systems for supplying heat to the tunnel 24 are
described in U.S. Pat. Nos. 5,277,105, 6,481,433 and 6,655,373, the
disclosures of which are incorporated herein by reference insofar as they
relate to heat delivery systems for ovens. These systems typically
include a heat source in the form of a single gas-fired burner (or other
heat source) for heating a plenum. For example, the burner can be located
at the front of the oven for heating a plenum located at the back of the
oven. Blowers are typically provided to move heat in the plenum through
passageways to metal fingers that open into the oven at appropriate
spacings from the conveyor belt to deliver streams of hot air onto food
products present on the conveyor, as discussed earlier. The heat source
is cycled on and off as necessary by a controller responding to signals
from temperature sensors (e.g., thermocouples) positioned, for example,
at the inlet and outlet ends of the oven tunnel.

[0059] In some embodiments of the present invention, uniform heating from
one end of the tunnel 24 to the other is achieved by apportioning the
tunnel 24 into two or more segments and by providing independent
temperature sensing and independent delivery of heated air to each
segment. This is shown diagrammatically in FIG. 4, where the oven 20 has
a pair of burners 60 and 62 with respective heating flames 64 and 66
supplying heat to respective independent plenums 68 and 70 associated
with segments 20A and 20B of the oven 20. The heat in plenums 68 and 70
is blown into the two oven segments 20A, 20B by separate blower fans 72
and 74 through holes 75 and 77 in groupings of top fingers 76 and 78 (and
through holes in corresponding groupings of bottom fingers, not shown)
associated with the respective oven segments 20A, 20B.

[0060] A number of different types of fans 72, 74 can be utilized for
supplying heated air within the oven 20, and can be driven by any type of
motor. As will be described in greater detail below, it is desirable in
some embodiments to control the speed of either or both fans 72, 74 based
at least in part upon one or more temperatures sensed within the oven 20,
one or more positions of food within, entering, or exiting the oven 20,
and/or the passage of one or more predetermined periods of time. To
provide control over fan speed based upon any of these factors, the fans
72, 74 can be driven by motors (not shown) coupled to and controlled by
the controller 42. In some embodiments, the fans 72, 74 are driven by
variable-speed motors coupled to and controlled by the controller 42.
Power can be supplied to each variable-speed motor by, for example,
respective inverters. In some embodiments, each inverter is a
variable-speed inverter supplying power to the motor at a frequency that
is adjustable to control the speed of the motor and, therefore, the speed
of the fan 72, 74. An example of such an inverter is inverter Model No.
MD60 manufactured by Reliance Electric (Rockwell Automation, Inc.). By
utilizing variable speed motors supplied by power through respective
inverters as just described, a significant degree of control over fan
speed and operation is available directly via the controller 42 connected
to other components of the control system.

[0061] The temperatures in each of the oven segments 20A, 20B can be
monitored by temperature sensors (e.g., thermocouples or other
temperature sensing elements) 80 and 82, which are shown in FIG. 4 as
being mounted near the inlet end 26 and the outlet end 28 of the oven 20.
Either or both temperature sensors 80, 82 can be located in respective
plenums 68, 70 as shown in the figures. In some alternative embodiments,
either or both temperature sensors 80, 82 are instead located within the
chamber through which the conveyor 22 moves. Either or both sensors 80,
82 can be positioned nearer the midpoints of the segments 20A, 20B or in
other locations, if desired. In addition to or in place of either or both
temperature sensors 80, 82, one or more position sensors 79, 81 and/or
83, 85 can be located to detect the position of a pizza on the conveyor
22, and to thereby control one or more operations of the oven 20 as a
result of such position detection (described in greater detail below).
Furthermore, in those embodiments in which the oven 20 is heated by one
or more gas burners, one or more gas output sensors (not shown) can be
positioned to detect the amount of fuel supplied to the oven 20. This
information can be provided to the controller 42 in order to control one
or more operations of the oven 20, such as to turn a conveyor 22 and/or
fan 72, 74 on or off, and/or to adjust the speed of the conveyor 22
and/or fan 72, 74.

[0062] The operation of the oven proceeds as shown in FIGS. 5A-5C, which
includes a diagrammatic representation of a pizza moving through the oven
tunnel 24 below graphs showing the changing BTU output of the burners 60,
62 and the corresponding blower output as the pizza advances through the
tunnel 24. Thus, a raw pizza 32R is shown in FIG. 5C resting on the
conveyor 22 before the pizza enters the oven tunnel 24. In the
illustrated embodiment of FIG. 5C, the oven 20 has been heated to a
desired temperature.

[0063] The oven 20 according to some embodiments of the present invention
can detect the presence of a raw pizza 32R on the conveyor 22 by a
position sensor 79, 81. The position sensor 79, 81 can take a number of
different forms, and need not necessarily comprise components on opposite
sides of the conveyor 22 as illustrated in FIG. 4. By way of example
only, the position sensor 79, 81 can be an optical sensor positioned to
detect the interruption of a beam of light (e.g., by a raw pizza 32R)
extending across the conveyor 22 at the entrance of the left tunnel
segment 20A, an infrared detector positioned to detect a raw pizza 32R
having a reduced temperature on the conveyor 22, a motion sensor
positioned to detect motion of a raw pizza 32R upon the conveyor 22, or
any other sensor capable of detecting the presence of the raw pizza 32R
on the conveyor 22. In the illustrated embodiment of FIG. 4, for example,
the position sensor 79, 81 comprises a light source 79 emitting a laser
or other beam of light across the conveyor 22 to a reflector 81, which
reflects the beam of light back to a photocell 81 (which may or may not
be associated with the light source 79). Alternatively, the light source
79 and the photocell 81 can be on opposite sides of the conveyor 22, in
which case an interruption in the beam of light can still be detected by
the photocell 81.

[0064] In those embodiments of the present invention employing a position
sensor 79, 81 at or adjacent the entrance of the left tunnel segment 20A
as just described, the position sensor 79, 81 can be coupled to the
controller 42, and can send one or more signals to the controller 42
responsive to the detection of a raw pizza 32R (or lack thereof) on the
conveyor 22. The controller 42 can be responsive to the position sensor
79, 81 by increasing the BTU output of either or both burners 60, 62. In
some embodiments, the controller 42 responds to the signal(s) from the
position sensor 79, 81 by increasing the BTU output of the burner 60 of
the left tunnel segment 20A, and can also respond to the signal(s) from
the position sensor 79, 81 by increasing the speed of either or both fans
72, 74. Either response can occur immediately or after a lag time, and
can occur relatively abruptly or gradually.

[0065] For example, the controller 42 can gradually increase the speed of
both fans 72, 74 from a slow, relatively quiet standby level 71 to a full
speed level 73, thereby supplying additional heat to both segments 20A
and 20B of the tunnel (although an increase supply of heat can instead be
provided to only one of the segments 20A, 20B in other embodiments). As
another example, the controller 42 can respond to the signal(s) from the
position sensor 79, 81 by quickly increasing the BTU output of the burner
60 of the left tunnel segment 20A, by gradually increasing the BTU output
of the burner 60 as the raw pizza 32R enters the left tunnel segment 20A,
or by quickly or gradually increasing the BTU output of the burner 60
only after a set period of time permitting either or both fans 72, 74 to
increase in speed. In these and other embodiments, the controller 42 can
respond to the signal(s) from the position sensor 79, 81 by gradually
increasing the BTU output of the burner 62 of the right tunnel segment
20, by gradually or quickly increasing the BTU output of the burner 62
following a lag time (e.g., a predetermined period of time that can be
independent or dependent upon the speed of the conveyor 22), or by
changing the BTU output of the burner 62 in any other manner.

[0066] If desired, the temperature sensor 80 can be used to detect the
presence of a raw pizza 32R on the conveyor 22. For example, as the raw
pizza 32R enters the oven 20 and approaches position 32(1), it draws heat
causing sensor 80 (FIG. 4) to call for the controller 42 to supply
additional gas to the burner 60 and/or to increase the speed of either or
both fans 72, 74. The controller 42 can respond to detection of the raw
pizza 32R by the temperature sensor 80 in any of the manners described
above with reference to the position sensor 79, 81. The position sensor
79, 81 and the temperature sensor 80 can be connected to the controller
42 in parallel, thereby enabling the controller 42 to change the BTU
output of the burner 60 and/or the speed of either or both fans 72, 74
based upon signals received by the position sensor 79, 81 or the
temperature sensor 80.

[0067] Until air in the plenum(s) 68, 70 has been sufficiently heated, the
above-described fan control generates a reduced amount of heat loss and
fan noise from the oven tunnel 24 into the surrounding environment, and
defines a load management setback of the oven 20. The establishment of a
quiet and reduced airflow standby state of the fan(s) 72, 74 is an
advantage of the load management setback. Also, while the fans 72, 74 in
the illustrated embodiment are operated in tandem, in alternate
embodiments they could be operated independently of one another (e.g., so
that the fan speeds are increased from their slower steady state level on
an independent "as-needed" basis). Finally, it is noted that the fans 72,
74 in the illustrated embodiment operate at about 2900 RPM at full speed
and at a level of about 1400 RPM when in the standby mode. The full speed
and standby speeds can vary depending at least in part upon design
constraints of the oven 20, the food being cooked, etc. For example, the
standby mode of either or both fans 72, 74 can be faster or slower as
desired, such as a 2100 RPM standby speed for both fans 72, 74.

[0068] With continued reference to the illustrated embodiment of the
present invention shown in FIGS. 5A-5C, as a pizza advances to the right
to position 32(2), the pizza is now warmed. Therefore, less heat is drawn
by the pizza, and the temperature in the first tunnel segment 20A rises.
In some embodiments, this temperature rise is detected by the temperature
sensor 80 of the first tunnel segment 20A, which can signal the
controller 42 to reduce the supply of gas to the left burner 60, thereby
producing a reduction in BTU output as shown in FIG. 5B. In these and
other embodiments, the controller 42 can be triggered to reduce the
supply of gas to the left burner 60 by a position sensor positioned in or
adjacent the first tunnel segment 20A to detect when the pizza has
advanced to a location in the first tunnel segment 20A. The position
sensor can have any of the forms described above with reference to the
position sensor 79, 81 at or adjacent the entrance to the left tunnel
segment 20A. The lowered BTU output level can continue for any part or
all of the remaining time that the pizza is in the first tunnel segment
20A (e.g., all of such time as shown in the illustrated embodiment of
FIG. 5B).

[0069] Next, the pizza reaches the position 32(3) shown in FIG. 5C, and
then passes the midpoint of the tunnel 24 between the two segments 20A,
20B. Since the pizza has exited, and there is therefore no further
significant perturbation to the heating environment in segment 20A, the
controller 42 can lower the gas supply (and therefore the BTU output) of
the left burner 60 to a reduced steady state. This reduction can be
triggered by a threshold temperature change detected by the temperature
sensor 80 in the first tunnel segment 20A and/or by the temperature
sensor 82 in the second tunnel segment 20B. Alternatively or in addition,
this reduction can be triggered by one or more signals from a position
sensor positioned to detect when the pizza has advanced to a location
between the first and second tunnel segments 20A, 20B (or near such a
location). The position sensor can have any of the forms described above
with reference to the position sensor 79, 81 at or adjacent the entrance
to the left tunnel segment 20A.

[0070] With continued reference to FIGS. 5A-5C, the right burner 62
supplies heat to the second tunnel segment 20B. The sensor 82
corresponding to the second tunnel segment 20B can initially detect a
spillover of heat from the first tunnel segment 20A (i.e., as the pizza
enters and is in the first part of the baking process in the first tunnel
segment 20A). Upon detection of sufficient spillover heat (e.g., when the
sensor 82 detects that a threshold temperature has been reached), the
sensor 82 can trigger the controller 42 to drop the initial BTU output of
the right burner 62. However, when the partially cooked pizza approaches
the right tunnel segment 20B, the pizza draws heat from the second tunnel
segment environment. This heat draw can also be detected by the sensor 82
of the second tunnel segment 20B, which can trigger the controller 42 to
supply additional gas to the burner 62 of the second tunnel segment 20B.
As a result, the BTU output of the right burner 62 can increase as the
pizza moves to and through positions 32(4), 32(5), and 32(6). The
reduction and increase of right burner BTU output just described can also
or instead be triggered by one or more signals from one or more position
sensors positioned in or adjacent the second tunnel segment 20B to detect
when the pizza has advanced to one or more locations within the oven 20.
The position sensor(s) can have any of the forms described above with
reference to the position sensor 79, 81 at or adjacent the entrance to
the left tunnel segment 20A.

[0071] In some embodiments, when the pizza leaves the position 32(6) and
begins exiting the tunnel 24, the temperature sensor 82 of the second
tunnel segment 20B can detect a rise in the tunnel temperature, and can
trigger the controller 42 to reduce the output of the right burner 62 as
shown in the BTU output graph of FIG. 5B. The resulting reduction in
temperature in the second tunnel segment 20B can also be detected by the
temperature sensor 80 of the first tunnel segment 20A due to heat
spillover between the two tunnel segments 20A, 20B, and can trigger the
controller 42 to increase the output of the left burner 60 to maintain
the steady state temperature between the two oven segments 20A, 20B.
Alternatively, the controller 42 can automatically increase the output of
the left burner 60 when the output of the right burner 62 is reduced (or
near in time to such reduction of the right burner 62). In some
embodiments, the controller 42 can also respond by returning the speed of
the fans 72, 74 to a standby state. This change in fan operation can take
place relatively abruptly or gradually, and can take place immediately
after a threshold temperature is detected by either or both sensors 80,
82 or after a predetermined period of time.

[0072] The increase of the left burner BTU output and the decrease in the
right burner BTU output just described can also or instead be triggered
by one or more signals from a position sensor positioned to detect when
the pizza is exiting or has exited the right tunnel segment 20B. For
example, the oven 20 illustrated in FIG. 4 has a position sensor 83, 85
(comprising a light source 83 and a photocell 85) that is substantially
the same as the position sensor 79, 81 at the entrance to the left tunnel
segment 20A described above. In other embodiments, the position sensor
83, 85 can have any of the forms described above with reference to the
position sensor 79, 81 at or adjacent the entrance to the left tunnel
segment 20A.

[0073] The position sensor 83, 85 and the temperature sensor 82 can be
connected to the controller 42 in parallel, thereby enabling the
controller 42 to change the BTU output of the burner 62 and/or the speed
of either or both fans 72, 74 based upon signals received by the position
sensor 83, 85 or the temperature sensor 82.

[0074] The BTU output of either or both burners 60, 62 can be controlled
by the controller 42 in any manner desired. For example, the gas supply
to either or both burners 60, 62 can be lowered or raised by the
controller 42 relatively abruptly or gradually upon detection of
threshold temperatures by either or both temperature sensors 80, 82,
after a set period of time, and/or after sufficient movement of the pizza
is detected by a position sensor.

[0075] Accordingly, in some embodiments, the controller 42 can control
either or both fans 72, 74 based at least in part upon the temperature
detected by a temperature sensor 80, 82, an amount of time elapsed
following a change in power supply to a burner 60, 62, and/or the
detection of a position of pizza or other food on the conveyor 22 by a
photo sensor 79, 81, 83, 85. For example, in some embodiments the speed
of either or both fans 72, 74 is increased after air driven by the fan(s)
72, 74 has been sufficiently heated.

[0076] Similarly, in some embodiments the controller 42 can control the
BTU output of either or both burners 60, 62 based at least in part upon
the temperature detected by a temperature sensor 80, 82, an amount of
time elapsed following a change in speed of a fan 72, 74, and/or the
detection of a position of pizza or other food on the conveyor 22 by a
photo sensor 79, 81, 83, 85. For example, in some embodiments the BTU
output of either or both burners 60, 62 is increased only after either or
both fans 72, 74 are brought up to a threshold speed.

[0077] In some embodiments, the oven 20 can include one or more
temperature sensors 93, 95 (e.g., thermocouples) coupled to the
controller 42 and positioned to detect the BTU output of either or both
burners 60, 62. Using such an arrangement of elements, a speed change of
the fans 72, 74 can be delayed for a desired period of time in order to
prevent undue cycling of the fans 72, 74 as temperatures rise and fall
within the tunnel 24 and as the BTU output of the burners 60, 62 rise and
fall. In this regard, as the BTU output detected by either or both
temperature sensors 93, 95 decreases below a threshold level, power to
either or both fans 72, 74 can remain unchanged for a set period of time,
after which time power to the fans 72, 74 can be reduced to a standby
speed of the fans 72, 74.

[0078] In the illustrated embodiment, for example, a relay 91 coupled to
the temperature sensors 93, 95, is also coupled to the controller 42, and
cooperates with the controller 42 to reduce power to either or both fans
72, 74 in a manner as just described. In this embodiment, when the output
of either burner 60, 62 falls below a threshold value (e.g., 60% of
maximum output in some embodiments), the relay 91 and controller 42 enter
into a timed state. When the output of either burner 60, 62 remains below
the threshold value for a set period of time (e.g., five minutes in some
embodiments), either or both burners 60, 62 are shut off. Either or both
burners 60, 62 can be re-activated in some embodiments by detection of a
sufficiently low threshold temperature by either of the tunnel segment
temperature sensors 80, 82, by sufficient movement of a pizza detected by
any of the position sensors described above, after a set period of time
has passed, and the like. Thus, as the BTU output of either or both
burners 60, 62 move above and below one or more threshold levels, the
tendency of the fans 72, 74 to cycle (e.g., between high and low speed
levels, and in some cases between on and off states) is reduced. Instead,
the fans 72, 74 can remain at a full speed level until a lowered BTU
level is established for at least the set period of time, such as for
five minutes in the illustrated embodiment.

[0079] Under some operating conditions, the BTU output of the burners 60,
62 in some embodiments can be reduced to a relatively low level (e.g., as
low as a 5:1 air to gas ratio, in some cases). A description of burner
features enabling this low BTU burner output is provided below.
Relatively low (and relatively high) burner BTU output can generate
problems associated with poor combustion. For example, relatively low
burner BTU output can generate incomplete combustion and flame lift-off.
To address these issues, the controller 42 in some embodiments of the
present invention is adapted to turn gas to either or both burners 60, 62
completely off in the event that either or both temperature sensors 80,
82 detect that a low threshold temperature has been reached.

[0080] In some of these embodiments, when either temperature sensor 80, 82
detects that a sufficiently low temperature has been reached, the
controller 42 responds by turning off gas to the burner 60, 62 associated
with that temperature sensor 80, 82 (either immediately or if a higher
temperature is not detected after a set period of time). The supply of
gas to the burner 60, 62 can be restored after a period of time and/or
after the temperature sensor 80, 82 detects a temperature below a lower
predetermined threshold temperature. In this manner, the burner 60, 62
can be cycled in order to avoid operating the burner 60, 62 at a very low
BTU output. As will be described in greater detail below, in some
embodiments two or more burners 60, 62 will always be on or off together.
In such cases, the controller 42 can respond to a low threshold
temperature by turning off the supply of gas to both burners 60, 62, and
can restore the supply of gas to both burners 60, 62 after a period of
time and/or after the temperature sensor 80, 82 detects that a lower
threshold temperature has been reached.

[0081] Similarly, in some embodiments, when either temperature sensor 80,
82 detects that a sufficiently high temperature has been reached, the
controller 42 responds by turning off gas to the burner 60, 62 associated
with that temperature sensor 80, 82 (either immediately or if a lower
temperature is not detected after a set period of time). The supply of
gas to the burner 60, 62 can be restored after a period of time and/or
after the temperature sensor 80, 82 detects a temperature below the low
threshold temperature or a sufficient drop in temperature. In this
manner, the burner 60, 62 can be cycled in order to avoid operating the
burner 60, 62 at a very high BTU output. As will be described in greater
detail below, in some embodiments two or more burners 60, 62 will always
be on or off together. In such cases, the controller 42 can respond to a
high threshold temperature by turning off the supply of gas to both
burners 60, 62, and can restore the supply of gas to both burners 60, 62
after a period of time and/or after the temperature sensor 80, 82 detects
a temperature below the low threshold temperature or an otherwise
sufficient drop in temperature.

[0082] Although only two tunnel segments 20A, 20B are used in the
illustrated embodiment, more than two tunnel segments can be used in
other embodiments, each such alternative embodiment having one or more
tunnel segments with any combination of the elements and features
described above with reference to the illustrated embodiment. Also, as
described above, the illustrated embodiment uses separate burners 60, 62
for each tunnel segment 20A, 20B. In other embodiments, it is possible to
achieve the desired segment-specific heating using a single burner and
conventional structure and devices to direct heat to each segment
independently in response to signals from temperature sensors associated
with each of the segments. Finally, although gas burner(s) are preferred,
other heating elements and devices can instead or also be used (e.g., one
or more electric heating elements). As used herein and in the appended
claims, the term "heating elements" refers to gas burners, electric
heating elements, microwave generating devices, and all alternative
heating elements and devices.

Energy Management

[0083] In some embodiments, it may be desirable to operate the oven 20 in
one or more energy saving modes. Components of the oven 20 that can be
controlled to provide energy savings may include either or both burners
60 and 62, either or both fans 72 and 74, and/or the conveyor 22.

[0084] Saving energy with the burners 60 and 62 may be achieved by
lowering the temperature threshold in one or both of the plenums 68 and
70 that the burners 60 and 62 heat. This lower threshold can cause one or
both of the burners 60 and 62 to be on less often, or to operate at a
lower output, resulting in energy savings. Additionally, one or both of
the burners 60 and 62 may be turned off completely.

[0085] Saving energy with the fans 72 and 74 may be achieved by reducing
the speed or RPMs of one or both of the fans 72 and 74 which can require
less power and, therefore, save energy. Additionally, one or both of the
fans 72 and 74 may be turned off completely.

[0086] Saving energy with the conveyor 22 may be achieved by slowing down
or turning off the conveyor 22.

[0087] While it may be possible to set the plenum temperature, fan speed,
and conveyor speed to any number of values between a minimum and a
maximum, it may be more practical to choose one or more settings in the
range between each minimum and maximum.

[0088] Energy management strategies may include controlling any one or
more of the burners 60, 62, fans 72, 74, and conveyor 22 of the oven 20
individually or in combination and/or controlling such components in the
different segments of the oven 20 individually or in combination.

[0089] Energy management events which cause one or more energy management
strategies described herein to execute may be triggered by one or more
actions, alone or in combination, including a predetermined amount of
elapsed time, feedback from one or more temperature sensors, feedback
from one or more position sensors, feedback from one or more motion
detectors, and the like.

[0090] FIG. 12 illustrates a process for an energy management mode that
can be utilized for a conveyor oven, such as the pizza oven 20 of FIG. 4.
At step 300, the controller 42 can check for the presence of a pizza on
conveyor 22. A pizza can be detected in any of the manners described
herein, such as by one or more optical sensors 79 and 81. If a pizza is
detected, a timer can be reset, either or both of the fans 72 and 74 can
be set to a higher speed, and/or either or both of the burners 60, 62 can
be set to a higher level to raise the temperature in one or both of the
plenums 68, 70 to a higher level (steps 305, 310, and 315). If no pizza
is detected by the sensors 79 and 81 (step 300), the controller 42 can
check a timer to determine the period of time since the last pizza was
put on the conveyor 22 (step 320). If the timer is less than a
predetermined threshold, the operation of the oven 20 can remain
unchanged and the controller 42 can continue to check for the presence of
a pizza (step 300). If the timer exceeds the predetermined threshold, the
controller 42 can go into an energy saving mode. In this energy saving
mode, either or both fans 72 and 74 can be set to a low speed and the
temperature can be set to a low value (steps 325 and 330). The controller
42 can then continue to check for the presence of a pizza on the conveyor
22 (step 300). The controller 42 can remain in this energy saving mode
until a pizza is detected on the conveyor 22 at step 300.

[0091]FIG. 13 illustrates another embodiment of a process for an energy
management mode that can be utilized for a conveyor oven, such as the
pizza oven 20 of FIG. 4. At step 335, the controller 42 can check for the
presence of a pizza on conveyor 22. A pizza can be detected in any of the
manners described herein, such as by one or more optical sensors 79 and
81. If a pizza is detected, a timer can be reset, either or both of the
fans 72 and 74 can be set to a higher speed, and/or either or both of the
burners 60, 62 can be set to a higher level to raise the temperature in
one or both of the plenums 68, 70 to a higher level (steps 340, 345, and
350). Since, as will be explained later, the oven temperature can be
relatively low (e.g., if the oven has been in an energy management mode),
it may be necessary to wait until the temperatures in the plenums 68 and
70 reach levels that will result in temperatures satisfactory for baking
when the pizza arrives in the respective plenums before allowing the
pizza on conveyor 22 to enter the oven 20. Therefore, at step 355, the
controller 42 can wait until the temperatures of the oven 20 reach their
thresholds.

[0092] Once the temperatures of the oven 20 reach their thresholds, the
conveyor 22 can start (step 360) and the pizza can enter the oven 20 and
bake. If no pizza is detected by the sensors 79 and 81 (step 335), the
controller 42 can check a timer to determine the period of time since the
last pizza was put on the conveyor 22 (step 365). If the timer is less
than a predetermined threshold, the operation of the oven 20 can remain
unchanged and the controller 42 can continue to check for the presence of
a pizza (step 335). If the timer exceeds the predetermined threshold, the
controller 42 can enter an energy saving mode. In this energy saving
mode, either or both fans 72 and 74 can be set to a low speed (step 370),
the burner 62 for either or both plenums 68, 70 can be turned off (e.g.,
the back plenum 70 can be turned off as indicated at step 375), and the
temperature in the first plenum 68 can be set to a lower level (step
380). The conveyor 22 can also be turned off (step 385). The controller
42 can then continue to check for the presence of a pizza on the conveyor
22 (step 335). The controller 42 can remain in this energy saving mode
until a pizza is detected on the conveyor 22 at step 335.

[0093]FIG. 14 illustrates another embodiment of a process for an energy
management mode that can be utilized for a conveyor oven, such as the
pizza oven 20 of FIG. 4. At step 400, the controller 42 can check for the
presence of a pizza on conveyor 22. A pizza can be detected in any of the
manners described herein, such as by one or more optical sensors 79 and
81. If a pizza is detected, a timer can be reset, either or both of the
fans 72 and 74 can be set to a higher speed, and/or either or both of the
burners 60, 62 can be set to a higher level to raise the temperature in
one or both of the plenums 68, 70 to a higher level (steps 405, 410, and
415). Since, as will be explained later, the oven temperature can be
relatively low (e.g., if the oven has been in an energy management mode),
it may be necessary to wait until the temperatures in the plenums 68 and
70 reach levels that will result in temperatures satisfactory for baking
when the pizza arrives in the respective plenums before allowing the
pizza on conveyor 22 to enter the oven 20. Therefore, at step 420, the
controller 42 can wait until the temperatures of the oven 20 reach their
thresholds.

[0094] Once the temperatures of the oven 20 reach their thresholds, the
conveyor 22 can start (step 425) and the pizza can enter the oven 20 and
bake. If no pizza is detected by the sensors 79 and 81 (step 400), the
controller 42 can check a timer to determine the period of time since the
last pizza was put on the conveyor 22 (step 420). If the timer is less
than a predetermined threshold, the operation of the oven 20 can remain
unchanged and the controller 42 can continue to check for the presence of
a pizza (step 400). If the timer exceeds the predetermined threshold, the
controller 42 can go into an energy saving mode. In this energy saving
mode, either or both fans 72 and 74 can be turned off (step 435), either
or both burners 60 and 62 can be turned off (step 440), and the conveyor
22 can be turned off (step 445). The controller 42 can then continue to
check for the presence of a pizza on the conveyor 22 (step 400). The
controller 42 can remain in this energy saving mode until a pizza is
detected on the conveyor 22 at step 400.

[0095]FIG. 15 illustrates another embodiment of a process for an energy
management mode that can be utilized for a conveyor oven, such as the
pizza oven 20 of FIG. 4. The process illustrated in FIG. 15 combines much
of the processes illustrated in FIGS. 12 and 13. At step 450, the
controller 42 can check for the presence of a pizza on conveyor 22. A
pizza can be detected in any of the manners described herein, such as by
one or more optical sensors 79 and 81. If a pizza is detected, a timer
can be reset, either or both fans 72 and 74 can be set to a high speed,
and the temperature can be set to a high level (steps 455, 460, and 465).
If no pizza is detected by the sensors 79 and 81 (step 450), the
controller 42 can check a timer to determine the period of time since the
last pizza was put on the conveyor 22 (step 470). If the timer is less
than a first predetermined threshold, the operation of the oven 20 can
remain unchanged and the controller 42 can continue to check for the
presence of a pizza (step 450). If the timer exceeds the first
predetermined threshold, the controller 42 can check the timer to
determine if it exceeds a second predetermined threshold (step 475). The
second predetermined threshold is a period of time that is longer than
the first predetermined threshold. If the timer does not exceed the
second predetermined threshold, the controller 42 can enter a first
energy saving mode.

[0096] In this first energy saving mode, either or both fans 72 and 74 can
be set to a low speed and the temperature can be set to a low value
(steps 480 and 485). The controller 42 can then continue to check for the
presence of a pizza on the conveyor 22 (step 450). The controller 42 can
remain in this first energy saving mode until a pizza is detected on the
conveyor 22 at step 450 or until the threshold period of time since the
last pizza was detected on the conveyor 22 (e.g., until the second
predetermined threshold of the timer is exceeded). If, at step 475, the
timer exceeds the second predetermined threshold, the controller 42 can
enter a second energy saving mode.

[0097] In the second energy saving mode, either or both burners 60, 62 can
be turned off (e.g., the burner 62 for the back plenum 70 can be turned
off as indicated at step 490), and the conveyor 22 can be turned off
(step 495). The controller 42 can then continue to check for the presence
of a pizza on the conveyor 22 (step 500). The controller 42 can remain in
this second energy saving mode until a pizza is detected on the conveyor
22 at step 500. If a pizza is detected at step 500, the timer can be
reset, either or both fans 72 and 74 can be set to a high speed, and the
temperature can be set to a high level (steps 505, 510, and 515). Since,
as will be explained later, the oven temperature can be relatively low
(e.g., if the oven has been in an energy management mode), it may be
necessary to wait until the temperatures in the plenums 68 and 70 reach
levels that will result in temperatures satisfactory for baking when the
pizza arrives in the respective plenums before allowing the pizza on
conveyor 22 to enter the oven 20. Therefore, at step 520, the controller
42 can wait until the temperature(s) of the oven 20 reach their
threshold(s). Once the temperatures of the oven 20 reach their
thresholds, the conveyor 22 can start (step 525) and the pizza can enter
the oven 20 and bake. The controller 42 can then exit the energy saving
modes and continue checking for pizzas at step 450.

[0098]FIG. 16 illustrates another embodiment of a process for an energy
management mode that can be utilized for a conveyor oven, such as the
pizza oven 20 of FIG. 4. The process illustrated in FIG. 16 combines much
of the processes illustrated in FIGS. 12, 13, and 14. At step 550, the
controller 42 can check for the presence of a pizza on conveyor 22. A
pizza can be detected in any of the manners described herein, such as by
one or more optical sensors 79 and 81. If a pizza is detected, a timer
can be reset, either or both fans 72 and 74 can be set to a high speed,
and the temperature can be set to a high level (steps 555, 560, and 565).
If no pizza is detected by the sensors 79 and 81 (step 550), the
controller 42 can check a timer to determine the period of time since the
last pizza was put on the conveyor 22 (step 570). If the timer is less
than a first predetermined threshold, the operation of the oven 20 can
remain unchanged and the controller 42 can continue to check for the
presence of a pizza (step 550). If the timer exceeds the first
predetermined threshold, the controller 42 can check the timer to
determine if it exceeds a second predetermined threshold (step 575). The
second predetermined threshold is a period of time that is longer than
the first predetermined threshold. If the timer does not exceed the
second predetermined threshold, the controller 42 can enter a first
energy saving mode.

[0099] In the first energy saving mode, either or both fans 72 and 74 can
be set to a low speed, and the temperature can be set to a low value
(steps 580 and 585). The controller 42 can then continue to check for the
presence of a pizza on the conveyor 22 (step 550). The controller 42 can
remain in this first energy saving mode until a pizza is detected on the
conveyor 22 at step 550 or until the threshold period of time since the
last pizza has been detected on the conveyor 22 (e.g., until the second
predetermined threshold of the timer is exceeded). If, at step 575, the
timer exceeds the second predetermined threshold, the controller 42 can
enter a second energy saving mode.

[0100] In the second energy saving mode, either or both burners 60, 62 can
be turned off (e.g., the burner 62 for the back plenum 70, can be turned
off as indicated at step 590), and the conveyor 22 can be turned off
(step 595). The controller 42 can then continue to check for the presence
of a pizza on the conveyor 22 (step 600). If a pizza is detected at step
600, the timer can be reset to zero, either or both fans 72 and 74 can be
set to a high speed, and the temperature can be set to a high level
(steps 605, 610, and 615). Since, as will be explained later, the oven
temperature can be relatively low (e.g., if the oven has been in an
energy management mode), it may be necessary to wait until the
temperatures in the plenums 68 and 70 reach levels that will result in
temperatures satisfactory for baking when the pizza arrives in the
respective plenums before allowing the pizza on conveyor 22 to enter the
oven 20. Therefore, at step 620, the controller 42 can wait until the
temperature(s) of the oven 20 reach their threshold(s). Once the
temperatures of the oven 20 reach their thresholds, the conveyor 22 can
start (step 625) and the pizza can enter the oven 20 and bake. The
controller 42 can then exit the energy saving modes and continue checking
for pizzas at step 550.

[0101] If no pizza is detected by the sensors 79 and 81 (step 600), the
controller 42 can check a timer to determine the period of time since the
last pizza was placed on the conveyor 22 (step 630). If the timer is less
than a third predetermined threshold, the operation of the oven 20 can
remain in the second energy saving mode, and the controller 42 can
continue to check for the presence of a pizza (step 600). The third
predetermined threshold is a period of time that is longer than the
second predetermined threshold. If the timer exceeds the third
predetermined threshold, the controller 42 can enter a third energy
saving mode. In this third energy saving mode either or both fans 72 and
74 can be turned off (step 635) and the first burner 60 can be turned off
(step 640). The controller 42 can then continue to check for the presence
of a pizza on the conveyor 22 (step 600). The oven 20 may remain in the
third energy savings mode until a pizza is detected at step 600. Once a
pizza is detected at step 600, processing continues at step 605 as
previously described.

[0102] Embodiments of three energy savings modes have been illustrated
along with two combinations of the illustrated energy savings modes.
Further embodiments can include, for example, combining the embodiments
of FIGS. 12 and 14 or FIGS. 13 and 14. Further, other methods of
controlling the components of the conveyor oven can be utilized to create
additional energy saving modes and combinations thereof.

[0103] As one skilled in the art will understand, numerous strategies and
combinations of strategies exist for implementing energy management for
an oven 20. Considerations in deciding which strategies to implement
include the time it will take to be ready for baking after entering an
energy saving mode and the amount of energy required to reach baking
temperature following an energy saving mode. As such it can be desirable
to provide multiple energy management strategies and allow users to
choose the strategy or combination of strategies that best meets their
needs.

[0104] In some embodiments, one or more remote input devices can provide
an indication to the controller 42 that food product (e.g., a pizza)
needs to be baked. Such remote input devices can change the operational
state of the oven 20, such as by providing trigger mechanisms (other than
those described elsewhere herein) to prepare the oven for cooking Remote
input devices can include one or more push buttons, switches, knobs,
keypads, operator interfaces, cash registers, or other user manipulatable
devices, one or more sensors (e.g., pressure sensors, limit switches,
optical sensors), a computer, and the like. The remote input device can
communicate with the controller 42 in any suitable manner, including a
hard-wired connection, a wireless connection, an internet connection, and
any combination of such connections.

[0105]FIG. 24 illustrates an exemplary layout of a kitchen 1000 for
cooking and serving pizzas. A counter 1005 can include one or more cash
registers 1010 for taking customer orders. In addition to the conveyor
oven 20, the kitchen 1000 can include a refrigerator 1015, a preparation
table 1020, a final preparation table 1030, and/or any number of other
food preparation and cooking stations and equipment. Other examples of
such cooking stations and equipment include walk-in coolers, sinks,
racks, food processing equipment (e.g., mixers, grills, and the like),
and the like. One or more remote devices can be associated with any of
such cooking stations or equipment, and can provide indication(s) that
food product needs to be prepared by the conveyor oven 20.

[0106] For example, in some embodiments, a switch or sensor of the
refrigerator 1015 can detect when the door of the refrigerator 1015 has
been opened, and can communicate with the controller 42 via link 1040. As
another example, in some embodiments, a switch or sensor of the
preparation table 1020 can detect that food product is being made (e.g.,
by detecting the weight of food product placed upon the preparation
table, optically detecting the presence of such food product, and the
like), and can communicate with the controller via link 1045. As another
example, in some embodiments, one or more cash registers 1010 can inform
the controller 42 via links 1050 and 1055 when a customer has ordered a
pizza. As yet another example, the conveyor oven 20 can be provided with
one or more proximity sensors adapted to detect the presence of a cooking
element (e.g., a cooking pan, tray, container, and the like) within a
range of distance from such sensors, and can communicate with the
controller via a link. In such cases, the sensor can be an RFID sensor,
an LED sensor, and the like, wherein the cooking element is adapted to be
recognized by the sensor, such as by being provided with an antenna on or
embedded within the cooking element. Other types of remote devices can be
used in place of or in addition to those just described to inform the
controller 42 that food product (e.g., one or more pizzas) needs to be
cooked, thereby enabling the controller 42 to change the operational
state of the oven 20 accordingly.

[0107] In some embodiments, the controller 42 receives an indication from
a remote device that a food product needs to be cooked (e.g., that a
pizza ordered by a customer at a cash register will need to be cooked).
The controller 42 can immediately exit any energy savings mode it is in
and enter an operating mode (e.g., a baking mode) where the conveyor 22
is turned on. In some embodiments, the speed of one or more fans 72, 74
can be increased and/or the heat output of one or more heating elements
60, 62 can be increased in the operating mode of the oven 20. Also, in
other embodiments, the controller 42 may keep the oven 20 in an energy
saving mode for a period of time before entering the operating mode. The
period of time the controller 42 keeps the oven 20 in the energy saving
mode can be determined based at least in part upon the temperature of the
oven 20 and/or a length of time until baking is to begin.

[0108] For example, after receiving an indication from a remote device
that food product needs to be cooked by the oven 20, the controller 42
can detect a temperature of the oven 20 and can compare the temperature
of the oven 20 to a desired cooking temperature. The controller 42 can
then calculate the length of time (or use a look-up table to determine
the length of time) the oven 20 needs to heat up from the present
temperature in the oven 20 to the desired cooking temperature. The
controller 42 can also know the amount of time from when the controller
42 receives the indication from the remote device until the food product
is actually ready to be cooked (e.g., the preparation time). If the time
needed to heat the oven 20 to the cooking temperature is less than the
preparation time, the oven 20 would reach the desired cooking temperature
before the food product is ready to be cooked if the oven began heating
up immediately upon receiving the indication from the remote device.
Therefore, the controller 42 can delay heating the oven 20, such as until
the remaining preparation time equals the amount of time needed to heat
the oven 20 to the desired cooking temperature.

[0109] In some embodiments, after receiving an indication from a remote
device that food product needs to be cooked by the oven 20, the
controller 42 can delay heating the oven 20 based at least in part upon a
known time by which the food product must be delivered or a desired
cooking completion time. The time to delivery can be based on a time of
day (e.g., shorter during lunch and longer during dinner) or a variable
time (e.g., the length of time until a delivery person will be available
to deliver the food product). The cooking completion time can be based
upon an anticipated dining rush or other event. The controller 42 can
know the length of time the oven 20 needs to reach the baking temperature
based at least in part upon the present temperature of the oven 20 as
discussed above. The controller 42 can also know the total cooking time
of the food product and the length of time needed after the food product
is cooked and before the food product is ready for serving or delivery
(final preparation time). For example, the controller 42 receives an
indication from a remote device that a pizza needs to be cooked. The
controller 42 knows that the total baking time combined with the final
preparation time is a certain length of time. If a delivery person will
not be available to deliver the pizza until some time later, the
controller 42 can determine when to heat the oven 20 based on when the
delivery person will arrive minus the baking and final preparation time,
and minus the time to heat the oven 20 to the baking temperature. In this
manner, the pizza can be hot and fresh when the delivery person is ready
to begin his or her delivery run.

[0110] After a cooking process is complete, the controller 42 can
automatically cause the oven 20 to enter or return to an energy saving
mode. This process can be delayed for a predetermined period of time in
order to prevent unnecessary cycling of the oven 20, can be overridden
based upon an indication of additional food product to be cooked (e.g.,
an indication from a remote device as described above), or can be
overridden based upon a reduction in oven demand (e.g., when the rate of
food product to be cooked falls to a predetermined threshold).

[0111] FIGS. 25A and B illustrate exemplary time lines for the operations
described above. The controller 42 (see FIG. 24) receives an indication
from a remote device that a pizza needs to be cooked at 1100. The
controller 42 can then determine when the pizza will be ready to be
placed on the conveyor 22 to be cooked (1105). The controller 42 knows
the preparation time of the pizza (the difference between 1105 and 1100
in FIG. 25A), and can determine when to exit an energy-savings mode and
to enter a heating mode (1110) by subtracting the heating time from the
preparation time to arrive at the baking mode time (1110). The pizza then
finishes baking at 1115 and is ready for delivery, following final
preparation at 1120.

[0112]FIG. 25B illustrates an exemplary time line for the operation of an
oven 20 when the time to delivery 1120 is greater than the total time
needed to prepare and cook a pizza. The controller receives (at 1100) an
indication from a remote device that a pizza needs to be cooked. The
controller 42 can know the delivery time 1120. The controller 42 can work
backward from the delivery time (1120) to determine the time to start
heating the oven (1110) by subtracting the final preparation time (the
difference between 1120 and 1115), the baking time (the difference
between 1115 and 1105), and the heating time (the difference between 1105
and 1110), wherein the heating time can be calculated based upon the
difference between the temperature of the oven and the desired baking
temperature.

[0113] In some embodiments, the controller 42 can enter an energy saving
mode immediately at 1115, provided a remote device has not indicated that
another pizza needs to be cooked. The controller 42 can also attempt to
maximize the energy savings by setting a target temperature of the oven
20, during an energy saving mode, such that the heating time is equal to
the difference between the time an indication that a pizza needs to be
cooked is received from a remote device (1100) and the time baking is to
begin (1105). This target temperature can add time (indicated by 1125) to
the heating time.

[0114] As described above, the controller 42 can receive one or more
indications from a remote device to change oven operation based upon an
anticipated demand for cooked food product. For example, in some
embodiments, the indication(s) can turn the oven 20 on, can increase the
heat output of one or more heating elements 60, 62, and/or can increase
the speed of one or more fans 70, 72. Also or in addition, different
portions of the oven 20 can be activated or de-activated in order to
increase or decrease the cooking capacity of the oven 20 based upon the
anticipated demand for cooked food product. Information reflecting the
anticipated demand for cooked food product can also be received from the
remote device(s), and can include data representing a quantity of food
product to be cooked and/or a rate of food orders received).

[0115] For example, an oven 20 can have two or more conveyors 22 for
moving food product through the oven 20. The conveyors 22 can be stacked,
can be side-by-side, or can have any other configuration described
herein. For example, in a "split conveyor" (in which two adjacent
conveyors 22 of the same or different width run in parallel), a first
conveyor 22 can be operated independently of a second conveyor 22, such
as by moving faster or slower than the second conveyor, in a direction
opposite the second conveyor, and the like. Feedback regarding either or
both conveyors 22 (e.g., speed, temperature, and the like) can be
provided to a controller 42 for display upon an operator interface and/or
for adjustment of oven operation in any of the manners described herein.
For example, the remote device can indicate to the controller 42 a
quantity of pizzas that need to be cooked. The controller 42 can then
determine if the first conveyor can cook the quantity of pizzas within a
desired time. If the first conveyor cannot meet the demand, the
controller 42 can cause the oven 20 to exit an energy saving mode (e.g.,
a mode in which the heating elements and/or fans associated with less
than all conveyors are in an operating mode). As a result, one or more
additional conveyors with associated heating elements and fans can be
brought up to operating temperature only as the demand for pizzas
requires. If the quantity of pizzas needing to be cooked approaches or
exceeds the maximum capacity of the conveyor(s) currently in an operating
mode, the controller 42 can put one or more other conveyors into an
operating mode or a stand-by mode in which such other conveyor(s) are
heated to a level above the energy savings mode but less than the baking
temperature.

[0116] It should be noted that the various energy-saving modes described
herein do not indicate or imply that the oven 20 is incapable of cooking
food product while in an energy saving mode. In some embodiments, an oven
20 can still cook food product while in one or more energy savings modes.
For example, one or more conveyors of a multiple-conveyor oven can enter
an energy saving mode while still being able to cook food product on one
or more other conveyors of the oven. As another example, a conveyor oven
20 in a period of low demand can operate with significantly less heat
and/or fan output while still cooking food product, such as by slowing
the conveyor 22 without significantly lengthening cooking time.

[0117] In some embodiments, the controller 42 can determine the amount of
time necessary to heat the oven 20 to the desired cooking temperature and
can use the cooking time, final preparation time, and the initial
preparation time to calculate a time when a pizza will be ready. The
controller 42 can then provide this time to a display to inform an
operator of the length of time necessary to prepare and cook the pizza.

Contiguous Burners

[0118] Many different heat sources can be used to independently supply
heating to each of the oven segments 20A, 20B, including a number of
different gas burner configurations. By way of example only, FIG. 6
illustrates a single burner of a contiguous multiple burner configuration
which has been found to be particularly useful. This burner 100 comprises
a housing (e.g., an outer tube 102 as shown in the illustrated
embodiment) attached to a mounting plate 104 which closes off the
proximal end of the outer tube 102. The outer tube 102 can have any shape
desired, and in some embodiments has a relatively elongated shape as
shown in the illustrated embodiment.

[0119] A smaller diameter venturi tube 106 is located within the outer
tube 102 and has open distal and proximal ends 107, 112. The venturi tube
106 can be generally centered with its longitudinal axis along the
longitudinal axis of the outer tube 102, although non-concentric
relationships between the venturi tube 106 and the outer tube 102 can
instead be employed. In some embodiments, the venturi tube 106 is secured
in place near its distal end 107 by a venturi support 108 encircling the
venturi tube 106 and secured within the inside diameter 109 of the outer
tube 102. In some embodiments, a section 111 of the distal end 107 of the
venturi tube 106 extends beyond the venturi support 108.

[0120] A gas orifice 110 can be located in the mounting plate 104, and can
be spaced from the proximal open end 112 of the venturi tube 106. In some
embodiments (see FIG. 6), the gas orifice 110 can be centered or
substantially centered with respect to the open proximal end 112 of the
venturi tube 106, although other non-centered relationships between the
venturi tube 106 and the gas orifice 110 are possible. The open proximal
end 112 of the venturi tube 106 receives pressurized gas from the gas
orifice 110, and serves as a primary air inlet to admit a flow of air 115
into the venturi tube 106. In other embodiments, air can enter the
proximal end 112 of the venturi tube 106 through apertures or gaps in the
end of the venturi tube 106, through one or more conduits coupled to the
venturi tube 106, or in any other manner. In some embodiments, powered
air is supplied to that portion of the outer tube 102 below the venturi
support 108. For example, a powered air supply can be coupled to the
outer tube 102 in the illustrated embodiment via a conduit 113 leading to
the outer tube 102.

[0121] The venturi support 108 can have any shape adapted to support the
venturi tube 106 and/or to at least partially separate an interior
portion of the outer tube 102 from a burn region 116 opposite the
proximal end 112 of the venturi tube 106. In some embodiments, the
venturi support 108 is substantially disc shaped (e.g., see FIG. 6A). The
venturi support 108 can have an opening 117 (e.g., a central circular
opening 117 as shown in FIG. 6A) which fits about the circumference of
the venturi tube 106. Also, one or more apertures can be defined within
the venturi support 108, and in some cases can be defined between the
venturi support 108 and the outer tube 102 and/or the venturi tube 106.
For example, in the illustrated embodiment, the venturi support 108 has
edges 119 and 121 that partially define open gaps 123 and 125 between the
circumference of the venturi support 108 and the inside diameter 109 of
the outer tube 102. These gaps 123, 125 can admit secondary air to the
burn region 116 opposite the proximal end 112 of the venturi tube 106 in
order to help support combustion as will be explained in greater detail
below. In an alternate embodiment, one or more adjustable shutters (e.g.,
a rotatable overlapping flap, wall, or disk) can be provided to adjust
the amount of secondary air admitted to the burn region 116.

[0122] In some embodiments, the venturi tube 106 can have a flame
retention member 118 which can help prevent lift-off of the flame from
the distal end 107 of the venturi tube 106. As seen in FIG. 6B, in some
embodiments the flame retention member 118 comprises a ring 120 spaced
from the inside diameter of the distal end 107 of the venturi tube 106,
thereby defining an annular space 122 between the ring 120 and the inside
diameter of the venturi tube 106. The ring 120 can be permanently or
releasably retained in place with respect to the venturi tube 106 in a
number of different manners, such as by one or more fingers, pins, clips,
or other fasteners, by an apertured disc, and the like. In the
illustrated embodiment, the ring 120 is retained in place by a corrugated
member 128 located within the annular space 122. The corrugated member
128 abuts the inside diameter of venturi tube 106 and the outside
diameter of the ring 120, and can be permanently attached to the venturi
tube 106 and/or the ring 120. Also, the corrugated member 128 can hold
the ring 120 in place with respect to the venturi tube 106 by friction
(e.g., between the corrugated member 128 and the venturi tube 106 and/or
between the corrugated member 128 and the ring 120.

[0123] In some embodiments, a target 124 is positioned opposite (and can
be spaced from) the distal end 107 of the venturi tube 106. This target
124 can be retained in this position with respect to the venturi tube 106
in any manner, including those described above with reference to the
retention of the ring 120 within the venturi tube 106. In the illustrated
embodiment, for example, the target 124 is held in place by arms 126
extending from the target 124 to the outer tube 102, although the arms
126 could instead extend to the venturi tube 106 or other adjacent
structure of the burner 100. The arms 126 can be permanently or
releasably attached to the outer tube 102 and/or to the target 124 in any
suitable manner, such as by welding, brazing, or riveting, by one or more
snap-fits or other inter-engaging element connections, by clips, clamps,
screws, or other fasteners, and the like. In the illustrated embodiment,
the arms 126 are attached to the outer tube 102 by frictionally engaging
the inside diameter 109 of the outer tube 102.

[0124] The target 124 can have a convex shape, with an apex extending
generally toward the distal end 107 of the venturi tube 106. This target
124 can act to spread a portion 135 of the flame 134 emitted from the
distal end 107 of the venturi tube 106, facilitating mixing of gas
escaping from the venturi tube 106 with primary air and secondary air
being supplied to this region through the venturi tube 106 and the gaps
123, 125, respectively. In other embodiments, the target 124 can be
substantially flat, can present a concave surface to the distal end 107
of the venturi tube 106, can have any other shape suitable for spreading
the flame 134 as described above, and can have an apex directed toward or
away from the distal end 107 of the venturi tube 106.

[0125] With continued reference to FIG. 6, in some embodiments the outer
tube 102 of the burner 100 is coupled to a flame tube 130, such as by
being received within an end of the flame tube 130. The flame tube 130
can include a number of air openings 132 in any arrangement or pattern,
thereby supplying further oxygen to the burning gas supporting the flame
134, which can extend into the flame tube 130 when the burner 100 is
turned on.

[0126] In some embodiments of the present invention, the oven 20 has at
least one pair of contiguous burners 100 and 150 of the design
illustrated in FIGS. 6-6B. A pair of such burners 100, 150 is illustrated
in FIGS. 7A and 7B. The outer tubes 102, 102' of the respective burners
100, 150 can be mounted to a common base plate 104, and can each be
fitted with a target 124, 124' as described above. Powered air for
combustion can be supplied to a venturi enclosure 152 (e.g., a venturi
box having a rectangular shape or any other shape desired) by way of an
inlet 154 connected to a source of powered air, as described in more
detail below.

[0127] In FIG. 7B, the cover of the venturi enclosure 152 has been removed
to expose a base 156 of the venturi enclosure 152. The venturi enclosure
152 can have a respective base for each burner 100, 150, or can have a
common base 156 (such as that shown in FIG. 7B). The base 156 illustrated
in FIG. 7B has a pair of openings 158 and 160 associated respectively
with each of the two burners 100, 150. Air supply tubes 162 and 164 can
extend from openings 158 and 160 to the outer surface of each respective
outer tube 102 and 102', with the distal edge of each air supply tube
162, 164 shaped to follow and to sealingly engage the contour of the
outer tubes 102, 102'. Outer tubes 102 and 102' can each have a
respective inlet 166 and 168 in communication with the air supply tubes
162, 164. Thus, powered air from a blower 155 (see FIG. 2) entering the
venturi enclosure 152 through the inlet 154 can pass through air supply
tubes 162 and 164 and through air inlets 166 and 168 in the outer tubes
102, 102' of the burners 100, 150. In the illustrated embodiment, this
powered air enters the venturi tubes 106 of the burners 100, 150 through
the proximal ends 107 of the venturi tubes 106, and also passes through
gaps 123 and 125 in the venturi support disks 108.

[0128] Gas can be supplied to the burners 100, 150 at their proximal ends
112 in any suitable manner, such as through a shared supply tube or
through respective supply tubes 170 and 172 as shown in FIGS. 7A and 7B.
The supply tubes 170, 172 shown in FIGS. 7A and 7B have been cut away to
facilitate viewing the rest of the burners 100, 150. The supply tube(s)
can be mounted to the burners 100, 150 in any manner, such as by one or
more clamps, braces, or other fixtures, and can be mounted to one or more
mounting frames, plates, or other structures adapted for this purpose. By
way of example only, the supply tubes 170, 172 in the illustrated
embodiment are mounted on brackets 174 and 176 attached to a common plate
178, which in turn is attached to the base plate 104 of the burners 100,
150. Either or both gas supply tubes 170, 172 can have any type of common
valve or respective valves in order to control the supply of gas to the
burners 100, 150. In the illustrated embodiment, for example, a threaded
valve pin 180, 182 on each supply tube 170, 172 can be advanced and
retracted for fine adjustment of gas supplied to the burners 100, 150
through orifices (not shown) in the gas supply tubes 170, 172 adjacent
the gas orifices 110 (see FIG. 6). The present design makes it possible
to use a single main gas valve with any number of contiguous burners, and
in some embodiments to also adjust each burner 100, 150 independently of
the others.

[0129] The distal ends of the outer tubes 102 and 102' in the illustrated
embodiment are shown in FIG. 8 (in which the target 124' has been removed
from the second burner 102'). In this figure, the outer tubes 102, 102'
are spot welded in place in a support plate 184. In other embodiments,
the support plate 184 is not required, in which case a common mounting
plate 104 (or respective mounting plates 104 coupled together in any
manner) can secure the outer tubes 102, 102' with respect to one another.
In those embodiments in which a support plate 184 is utilized, the
support plate 184 can be attached to the outer tubes 102, 102' in any
manner, such as in any of the manners of attachment described above with
reference to the attachment of the arms 126 to the outer tube 102. Also,
in some embodiments, the outer tubes 102, 102' and the burners 100, 150
can be secured in place with respect to one another by a common support
plate 184 (or by respective support plates coupled together in any
manner) without this function being performed by one or more mounting
plates 104 as described above.

[0130] With reference again to FIG. 8, one burner 150 is provided with an
igniter 186, which produces a spark to ignite gas escaping from the
distal end 107 of venturi tube 106 (see FIG. 6). The flame produced
crosses over to the other burner 150 by way of a cross-over structure
which will be discussed below. The burner 150 can be provided with a
flame sensor 188 as a fail-safe measure to shut off the gas supply to
both burners 100, 150 should the flame produced in burner 150 fail to
cross over to the adjacent contiguous burner 100. In some embodiments,
each burner 100, 150 can be provided with a respective flame sensor 188
that can trigger gas shut-off when no flame is detected from the
corresponding burner 100, 150 after a sufficient period of gas supply
time has elapsed. Also, in some embodiments (e.g., where independent
burners 100, 150 are used to deliver heat to each of the oven segments),
each burner 100, 150 can have its own independent igniter 186.

[0131] In some embodiments of the present invention, the outer tubes 102
and 102' of the burners 100, 150 are each provided with at least one
aperture 200, 202 (see FIGS. 9A and 9C) through which fluid communication
is established between the burn regions 116 of the burners 100, 150. By
such fluid communication, heat from a flame 134 ignited in one of the
burners 100, 150 can raise the temperature in the other burner 150, 100
sufficiently to ignite the other burner 150, 100.

[0132] The aperture(s) 200, 202 in each of the outer tubes 102, 102' can
be rectangular, round, oval, irregular, or can have any other shape
desired. Also, the apertures 200, 202 can be open to or located a
distance from the ends of the outer tubes 102, 102' adjacent the burn
regions 116 (e.g., see FIGS. 6 and 9A), and can extend in a direction
away from the respective venturi tubes 106 to locations past the targets
124, 124'. In the illustrated embodiment, for example, each of the outer
tubes 102, 102' has a substantially rectangular aperture 200, 202 located
a distance from the end of the respective outer tube 102, 102' adjacent
the region 116.

[0133] The apertures 200, 202 in the outer tubes 102, 102' can, in some
embodiments, be joined by a conduit 212 extending between the apertures
200, 202. Such a conduit 210 can help direct heat to an unlit burner 100,
150 to a lit burner 150, 100 in order to light the unlit burner 100, 150.
The conduit 210 can have any shape desired, such as a substantially
rectangular or round cross-sectional shape, an irregular shape, and the
like. The conduit 210 can be enclosed or partially enclosed, and in the
illustrated embodiment of FIGS. 9A-9D is enclosed on all sides by top,
bottom, front, and back plates 204, 206, 208, and 210, respectively. The
plates 204, 206, 208, 210 or other elements used to define the conduit
212 can be sealed to one another and to the outer tubes 102, 102', such
as by fluid-tight welds, brazing, and the like. Such seals can protect
the interior of the conduit 212 from the surrounding environment.

[0134] Thus, when gas passing through a first burner 100 is ignited, the
flame produced at the distal end 107 of the venturi tube 106 in the first
burner 100 can cross over through the conduit 212 to the distal end 107
of the venturi tube 106' in the second burner 150, thereby igniting the
contiguous second burner 150. In such embodiments, the two burners 100,
150 are therefore either always on or always off together. Furthermore,
should the flame 134 in the first burner 100 fail to cross over or be
lost in the second burner 150, the sensor 188 (if employed) can signal
the controller 42, which can respond by cutting off gas to both burners
100, 150. This arrangement thus makes it possible to avoid situations in
which only one of two burners 100, 150 is lit and operating.

[0135] As described above, powered air can be supplied to both burners
100, 150 by a common venturi enclosure 152 (see FIG. 7A). In some
alternative embodiments, one of the burners can be coupled to a powered
source of air, and can be coupled to the other burner through an air
supply conduit in order to feed air to the other burner. An example of
such an alternative embodiment is illustrated in FIG. 10. In the
illustrated embodiment of FIG. 10, powered air is supplied to the
interior of the first burner 250 through a port 252, an air supply
conduit 254, and a side of the outer tube 256 of the first burner 250.
Air is supplied to the second burner 262 through another port (not shown)
in the outer tube 256 of the first burner 250, through another air supply
conduit 258, and through the side of the outer tube 260 of the second
burner 262.

[0136] While the illustrated embodiments of FIGS. 7A-10 each have a pair
of burners 100, 150, 250, 262, other embodiments can utilize more than
two burners by interconnecting additional contiguous burners (e.g.,
through any combination of common or connected mounting plates 104,
common or connected support plates 184, venturi enclosure(s) 152 shared
by burners, flame ignition conduits 212 extending between burners, and/or
air supply conduits 258 extending between burners as described above and
illustrated in the figures). Furthermore, although a common source of
powered air can be used to supply air to two or more burners 110, 150,
250, 262 (as shown in the illustrated embodiments), air can be supplied
to the individual burners 100, 150, 250, 262 on an individual basis.
Additionally, the burners 100, 150 and 250, 262 of the burner assemblies
described and illustrated herein are of the same size. However, in other
embodiments, the burners 100, 150 and 250, 262 can be different in size
(e.g., the second burner 150, 262 can be smaller than the first burner
100, 250 in applications in which the first burner 100, 250 supplies an
inlet tunnel segment 20A, 20B of the oven 20 and the second burner 150,
262 supplies the outlet tunnel segment 20B, 20A of the oven 20).

[0137] Returning now to the design of burner 100 illustrated in FIG. 6, it
is noted that the burner 100 has the ability to produce heat in an
unusually wide BTU range. In this regard, it should be noted that burners
of this general type typically operate at an air to gas ratio variability
of 3:1. However, the relatively low BTU draw required of burners in some
applications according to the present invention (e.g., in more efficient
ovens 20 employing one or more features of the present invention
described earlier) can call for an air to gas ratio variability as low as
6:1. Such a lean fuel mixture can result in flame lift-off from
conventional burners. Also, a rich air to gas ratio can result in poor
combustion. By employing the burner features described above, including a
reduced primary air input at the proximal end 112 of the venturi tube
106, a secondary air supply (e.g., via gaps 123, 125 in the illustrated
embodiments), and/or the air openings 132 in the flame tube 130, a much
richer gas supply can be provided to the burners 110, 150, 250, 262.
Also, it has been found that reduced primary air, combined with the
addition of the secondary air supply and the flame tube air openings 132
supports a reduced gas supply level, and hence a reduced BTU production
without flame lift off or dirty burning (encountered when there is
insufficient oxygen to support the flame 134).

[0138] FIG. 11 is a top plan view of selected elements of the oven 20
illustrated in FIGS. 1-4. Gas inlets 251, 253 are coupled to and supply
gas to the gas supply tubes 170, 172, respectively (all of which are
shown on the outside of the front wall 254 of the oven 20), which lead to
the burners 102, 102' (see FIGS. 7A and 7B). Also, the blower 155
supplies air to the venturi enclosure 152 via the air inlet 154 as
described above. Extending from the other side of the front wall 254 are
the flame tubes 130 and 130'. A barrier 258 is located at the distal ends
256 and 256' of the flame tubes 130, 130' and is positioned between the
two flame tubes 130, 130'. The barrier 258 can be a plate or any other
structure separating the flames 134 of the two tube flame tubes 130, 130'
from each other. Alternatively or in addition, the barrier 258 can be
positioned to separate the heater plenums 68, 70 from each other (e.g.,
can extend downwardly between the heater plenums 68, 70 in the
illustrated embodiment of FIG. 11), so that heat produced by the first
burner 100 associated with one flame tube 130 is directed into one heater
plenum 70, and heat produced by the second burner 150 associated with the
other flame tube 130' is directed into the other heater plenum 68.

Operator Interface

[0139]FIG. 17 is a schematic illustration of an alternative embodiment of
the control system for the oven 20. In the illustrated embodiment of FIG.
17, a microprocessor-based controller 42' (e.g., model FP0-C14
manufactured by Panasonic) can be coupled to a separate operator
interface 690 (e.g., model GT-30 manufactured by Panasonic).
Alternatively, the controller 42' and the operator interface 690 can be
incorporated into the same unit, if desired. The operator interface 690
can include a touchscreen display for displaying data from and/or
inputting data to the controller 42'.

[0140] In some embodiments, the operator interface 690 can include a color
liquid crystal display ("LCD") and can have a diagonal screen size of
5.7''. The resolution of the display can be 320 pixels by 240 pixels and
can support sixteen colors. Other embodiments of the operator interface
690 can include a monochrome display and/or can be of other sizes, color
depths, and resolutions.

[0141] FIGS. 18 to 23 illustrate displays for monitoring and controlling
the oven 20 according to an embodiment of the present invention. In some
embodiments, the operator interface 690 includes two or more different
screens for access by a user (e.g., oven operator, oven service or setup
personnel, and/or oven manufacturers) in order to control operation of
the oven 20. A significant advantage of this feature is the ability to
hide one or more screens from some users (e.g., oven operators), while
still enabling other users (e.g., oven service or setup personnel and/or
oven manufacturers) to access and adjust controls of the oven 20. Screens
and user operable controls can be hidden from users by the use of buttons
or other icons that are not normally visible on the operator interface
690, by password protection, and the like.

[0142] The use of multiple screens enables users to quickly access a
greater number of controls organized in an intuitive and logical manner,
thereby providing the user with enhanced control over oven operation. In
some embodiments, multiple screens having respective user-operable
controls can be navigated by selecting buttons or other icons on the
interface 690. Such screens can resemble windows, or can have any other
appearance and format desired.

[0143] FIGS. 18A and 18B show two embodiments of a main screen 700 of the
operator interface 690. The main screen 700 can include an on/off button
705. In some embodiments, the on/off button 705 can be a first color
(e.g., red) or shade when the oven 20 is off and can be a second color
(e.g., green) or shade when the oven 20 is on. In these and other
embodiments, text or symbols of the on/off button 705 can change to
indicate whether the oven 20 is on or off. Pressing the on/off button 705
when the oven 20 is off can signal the controller 42' to turn the burners
60 and 62 and the fans 72 and 74 on. The oven 20 can then warm up to a
predetermined temperature under control of the controller 42'. Pressing
the on/off button 705 when the oven 20 is on can signal the controller
42' to turn off the burners 60, 62 and/or fans 72, 74. In some
embodiments, the controller 42' turns off the fans 72, 74 only if the
temperature of the oven 20 is below a predetermined threshold. In such
embodiments, if the temperature of the oven 20 is above the predetermined
threshold, the controller 42' can continue to run the fans 72, 74 until
the temperature of the oven 20 falls below the predetermined temperature.

[0144] In some embodiments of the oven 20, the conveyor 22 can include a
single belt. When the oven 20 is on, the operator interface 690 can
display a belt #1 speed indicator/button 710. In some embodiments, the
speed of belt #1 can be shown in minutes and seconds, and can indicate
the length of time an item placed on the conveyor 22 takes to traverse
through the oven 20. In some embodiments of the oven 20, the conveyor 22
can include a second belt, belt #2. FIG. 18B illustrates an embodiment of
a main screen 700 for an oven 20 with a conveyor 22 including two belts.
A belt #2 speed indicator/button 715 can show the speed of belt #2 in
minutes and seconds. In ovens 20 with two side-by-side belts, the speed
of belt #1 can indicate the time an item placed on a first conveyor 22
takes to traverse through the oven 20, whereas the speed of belt #2 can
indicate the time an item placed on a second conveyor 22 takes to
traverse through the oven 20. In those embodiments in which the conveyors
22 are placed in an end-to-end arrangement, the sum of the times for belt
#1 and for belt #2 can indicate the length of time an item takes to
traverse the plenums 68 and 70 of the oven 20.

[0145] Pressing the speed of belt #1 indicator/button 710 can, in some
embodiments, display a data entry screen (not shown) to enable
modification of the speed setting for belt #1. The data entry screen can
display a keypad, a scroll bar, radio buttons, dials, slides, or any
other user control allowing an operator to enter a new data value. The
data entry screen can have an enter button which can enter a new data
value and return to the previous screen, and can also have a cancel
button which can return to the previous screen 755 without modifying the
data value. Pressing the speed of belt #2 indicator/button 715 can, in
some embodiments, display a data entry screen to allow modification of
the speed setting for belt #2 in any of the manners just described in
connection with the speed of belt #1 indicator/button 710.

[0146] In some embodiments, a first bar graph 720 can be displayed along
the left side of the main screen 700, and can indicate the percentage of
time the first burner 60 has been on during the period the oven 20 has
been on. Also or alternatively, a first alphanumeric display 725 can show
the percentage of time the first burner 60 has been on. In those
embodiments in which the first alphanumeric display 725 is used in
conjunction with the first bar graph 720, the first alphanumeric display
725 can be located anywhere adjacent the first bar graph 720, such as
above the first bar graph 720 as shown in FIGS. 18A and 18B. In some
embodiments, the first bar graph 720 and/or the first alphanumeric
display 725 can be a first color (e.g., green) or shade when the
percentage is below a predetermined threshold and can be a second color
(e.g., red) or shade when the percentage is above the predetermined
threshold. If desired, the first bar graph 720 and/or the first
alphanumeric display 725 can be displayed in a plurality of colors to
indicate additional thresholds or ranges.

[0147] In some embodiments a second bar graph 730 can be displayed along
the right side of the main screen 700 and can indicate the percentage of
time the second burner 62 has been on during the period the oven 20 has
been on. Also or alternatively, a second alphanumeric display 735 can
show the percentage of time the second burner 62 has been on. In those
embodiments in which the second alphanumeric display 735 is used in
conjunction with the second bar graph 730, the second alphanumeric
display 735 can be located anywhere adjacent the second bar graph 730,
such as above the second bar graph 730 as shown in FIGS. 18A and 18B. In
some embodiments, the second bar graph 730 and/or the second alphanumeric
display 735 can be a first color (e.g., green) or shade when the
percentage is below a predetermined threshold and can be a second color
(e.g., red) or shade when the percentage is above the predetermined
threshold. If desired, the second bar graph 730 and/or the second
alphanumeric display 735 can be displayed in a plurality of colors to
indicate additional thresholds or ranges.

[0148] It will be appreciated that the information provided by first and
second bar graphs 720, 730 can be displayed in a number of other forms,
including without limitation by pie charts, a series of ramped bars, and
the like. Also, the location and size of the first and second bar graphs
720, 730 shown in FIGS. 18A and 18B are presented by way of example only,
and can be different in other embodiments.

[0149] In some embodiments, the main screen 700 can also include a message
display 740 for displaying operating (e.g., energy mode) and/or error
messages. Also, the main screen 700 can include a time display 745. The
message and time displays 740, 745 can have any size and can be located
anywhere on the main screen 700 as desired.

[0150] The main screen 700, in some embodiments, can include a temperature
display/button 750 which can show a temperature of the oven. The
temperature displayed can be that of either plenum 68, 70, or can be an
average temperature of the plenums 68, 70. In some embodiments, two
temperature displays are provided, each showing a temperature of a
respective portion of the oven 20. Also, in some embodiments, pressing
the temperature display/button 750 can display a temperature setting
screen 755 (FIG. 19, described in greater detail below).

[0151] In some embodiments, the main screen 700 can include one or more
buttons for accessing one or more oven set-up screens. The buttons can be
visible or invisible, and can be password protected, if desired. In the
illustrated embodiment of FIGS. 18A and 18B, for example, the main screen
700 includes three hidden buttons 760, 765, and 770 to access respective
set-up screens. The hidden buttons 760, 765, and 770 have no visible
features displayed on the main screen 700, but react when pressed. The
first hidden button 760 can provide access to a temperature tuning screen
775 (FIG. 20). The second hidden button 765 can provide access to a belt
tuning screen 777 (FIG. 21) and the third hidden button 770 can provide
access to a belt set-up screen 778 (FIG. 22). Ovens 20 according to
embodiments of the present invention can have any one or more (or none)
of these screens 775, 777, 778.

[0152] FIG. 19 illustrates a temperature setting screen 755 according to
an embodiment of the present invention. The temperature setting screen
755 can display the first bar graph 720, the second bar graph 730, the
first alphanumeric display 725, and the second alphanumeric display 735
in a manner similar to that discussed previously with regard to the main
screen 700. The temperature setting screen 755 can also display actual
and/or desired temperatures for one or more portions of the oven 20. For
example, the temperature setting screen 755 illustrated in FIGS. 18A and
18B can display a first actual temperature 780 indicating the temperature
in the left oven segment 20A, and a second actual temperature 785
indicating the temperature in the right oven segment 20B. The temperature
setting screen 755 can also or instead display a first temperature
setpoint 790 for the left oven segment 20A and a second temperature
setpoint 795 for the right oven segment 20B.

[0153] The temperature setpoints can be target temperatures that the
controller 42' can attempt to maintain in each oven segment 20A, 20B. In
some embodiments, pressing the first temperature setpoint display 790 for
the left oven segment 20A can display a data entry screen (as discussed
previously) to allow modification of the first temperature setpoint,
while pressing the second temperature setpoint display 795 for the right
oven segment 20B can also display a temperature entry screen (as
discussed previously) to allow modification of the second temperature
setpoint. The temperature setting screen 755 can also be provided with a
back button 800 that can be pressed to display the main screen 700.

[0154] With reference again to the illustrated embodiment of the main
screen 700 in FIGS. 18A and 18B, pressing the hidden button 760 on the
main screen 700 of the operator interface 690 can display a temperature
tuning screen 775 as shown in FIG. 20. The temperature tuning screen 775
can enable an operator to monitor and modify control parameters of the
oven 20. Some embodiments of the oven 20 can use a proportional integral
derivative ("PID") control scheme. For example, the controller 42' can
utilize a PID control scheme for controlling the burners 60 and 62. The
PID control scheme enables the controller 42' to achieve and maintain the
temperatures within the oven segments 20A, 20B close to their temperature
setpoints.

[0155] In some embodiments, the temperature tuning screen 775 can include
one or more PID displays for one or more respective burners 60, 62 of the
oven 20. For example, in the illustrated embodiment of FIG. 20, the
temperature tuning screen 775 displays a burner #1 proportional gain
indicator/button 810, a burner #1 integral time indicator/button 815, a
burner #1 derivative time indicator/button 820, and a burner #1 control
cycle time indicator/button 825. In some embodiments, an operator can
press any of these indicators 810, 815, 820, 825 to display a data entry
screen (as discussed previously), thereby allowing modification of each
parameter. Alternatively or in addition, pressing a burner #1 autotune
button 830 can instruct the controller 42' to perform an autotuning
function that can automatically determine the optimum value for each of
the parameters.

[0156] The temperature tuning screen 775 can also display a burner #2
proportional gain indicator/button 835, a burner #2 integral time
indicator/button 840, a burner #2 derivative time indicator/button 845,
and a burner #2 control cycle time indicator/button 850. In some
embodiments, an operator can press any of these indicators 835, 840, 845,
850 to display a data entry screen (as discussed previously), thereby
allowing modification of each parameter. Alternatively or in addition,
pressing a burner #2 autotune button 855 can instruct the controller 42'
to perform an autotuning function that can automatically determine the
optimum value for each of the parameters.

[0157] In some embodiments, the temperature tuning screen 775 can display
one or more buttons for accessing set-up screens for energy saving modes.
It will be appreciated that such buttons can also or instead be located
on other screens of the operator interface 690. With reference to the
embodiment of FIG. 20, an energy saving mode #2 button 860 can access an
energy saving mode #2 screen 865 (FIG. 23A). The energy saving mode #2
screen 865 can display the time that the oven 20 is to remain in energy
saving mode #2 once the oven 20 enters energy saving mode #2. The energy
saving mode #2 screen 865 can include a mode #2 hours indicator/button
870, a mode #2 minutes indicator/button 875, and a mode #2 seconds
indicator/button 880. In some embodiments, pressing any of these
indicator/buttons 870, 875, 880 can display a data entry screen (as
discussed previously), enabling an operator to modify the time setting
for energy saving mode #2. The energy saving mode #2 screen 865 can also
be provided with a back button 800 for returning to the temperature
tuning screen 775.

[0158] The temperature tuning screen 775 can also display an energy saving
mode #3 button 885. Pressing the energy saving mode #3 button 885 can
access an energy saving mode #3 screen 890 (FIG. 23B). The energy saving
mode #3 screen 890 can display the time that the oven 20 is to remain in
energy saving mode #3 once the oven 20 enters energy saving mode #3. The
energy saving mode #3 screen 890 can include a mode #3 hours
indicator/button 895, a mode #3 minutes indicator/button 900, and a mode
#3 seconds indicator/button 905. In some embodiments, pressing any of the
indicator/buttons 895, 900, 905 can display a data entry screen (as
discussed previously), enabling an operator to modify the time setting
for energy saving mode #3. The energy saving mode #3 screen 890 can also
be provided with a back button 800 for returning to the temperature
tuning screen 775.

[0159] The temperature tuning screen 775 can also display an energy saving
mode #4 button 910. Pressing the energy saving mode #4 button 910 can
access an energy saving mode #4 screen 915 (FIG. 23c). The energy saving
mode #4 screen 915 can display the time that the oven 20 is to remain in
energy saving mode #4 once the oven 20 enters energy saving mode #4. The
energy saving mode #4 screen 915 can include a mode #4 hours
indicator/button 920, a mode #4 minutes indicator/button 925, and a mode
#4 seconds indicator/button 930. In some embodiments, pressing any of the
indicator/buttons 920, 925, 930 can display a data entry screen (as
discussed previously), enabling an operator to modify the time setting
for energy saving mode #4. The energy saving mode #4 screen 915 can also
be provided with a back button 800 for returning to the temperature
tuning screen 775.

[0160] In some embodiments, the main screen 700 is provided with a back
button 800, which can be pressed to return the user to the main screen
700.

[0161] With reference again to the illustrated embodiment of the main
screen 700 in FIGS. 18A and 18B, pressing the second hidden button 765 on
the main screen 700 of the operator interface 690 can display a belt
tuning screen 777 (FIGS. 21A and 21B). FIG. 21A is an embodiment of a
display for an oven 20 having a single belt, and FIG. 21B is an
embodiment of a display for an oven 20 having two belts. As with
temperature control of the oven 20 described above, some embodiments of
the controller 42' can control the operation of the belts using a PID
control scheme. The belt tuning screen 777 can enable an operator to
monitor and modify the parameters of the PID control.

[0162] The belt tuning screen 777 illustrated in FIG. 21A displays a front
belt proportional gain indicator/button 935, a front belt integral time
indicator/button 940, a front belt derivative time indicator/button 945,
and a front belt control cycle time indicator/button 950. In some
embodiments, an operator can press any of these indicator/buttons 935,
940, 945, 950 to display an entry screen, thereby enabling the operator
to modify each parameter. Alternatively or in addition, pressing a front
belt autotune button 955 can instruct the controller 42' to perform an
autotuning function that can automatically determine the optimum value
for each of the parameters.

[0163] The belt tuning screen 777 for an oven 20 with two belts can also
display a back belt proportional gain indicator/button 960, a back belt
integral time indicator/button 965, a back belt derivative time
indicator/button 970, and a back belt control cycle time indicator/button
975. An operator can press any of these indicators 960, 965, 970, 975 to
display an entry screen, thereby enabling the operator to modify each
parameter. Alternatively or in addition, pressing a back belt autotune
button 980 can instruct the controller 42' to perform an autotuning
function that can automatically determine the optimum value for each of
the parameters.

[0164] In some embodiments, the belt tuning screen 777 is provided with a
back button 800, which can be pressed to return the user to the main
screen 700.

[0165] With reference again to the illustrated embodiment of the main
screen 700 in FIGS. 18A and 18B, pressing the third hidden button 770 on
the main screen 700 can display a belt set-up screen 778 (see FIG. 22).
In some embodiments, the belt set-up screen displays different buttons
for two or more different belt lengths of the belts used in the conveyor
20. In the illustrated embodiment of FIG. 22, for example, the belt
set-up screen 778 displays three buttons 1000, 1005, 1010 representing
different belt lengths for a front belt of the conveyor 22, and three
buttons 1015, 1020, 1025 representing different belt lengths for a back
belt of the conveyor 22. The buttons can represent a front belt
short-length belt 1000, a front belt mid-length belt 1005, a front belt
long-length belt 1010, a back belt short-length belt 1015, a back belt
mid-length belt 1020, and a back belt long-length belt 1025.

[0166] In some embodiments the button for the belt length selected for
each belt can be displayed in a first color (e.g., green) or shade, and
the buttons for the belt lengths not selected can be displayed in a
second color (e.g., red) or shade. Pressing a button that is not
presently selected can make the belt length associated with the pressed
button become the active belt length, and can deselect the belt length
previously selected. Pressing a button that is already selected for at
least one of the belts of the conveyor 22 can deselect the belt length
associated with that button, placing that belt into an inactive mode
(e.g., a mode where the oven 20 has only one belt). In some embodiments,
pressing a button that is already selected for one of the belts of the
conveyor 22 has no impact on the oven 20. Also, in some embodiments, a
front belt active display 1030 and a back belt active display 1035 can
display in a first color (e.g., green) or shade when a belt length has
been selected for that belt and can display in a second color (e.g., red)
or shade when no belt length is selected. In these and other embodiments,
text associated with the front belt length and the back belt length can
change to indicate whether a belt length has been selected or no belt
length has been selected. In some embodiments, the belt set-up screen 778
is provided with a back button 800, which can be pressed to return the
user to the main screen 700.

[0167] The embodiments described above and illustrated in the figures are
presented by way of example only and are not intended as a limitation
upon the concepts and principles of the present invention. As such, it
will be appreciated by one having ordinary skill in the art that various
changes in the elements and their configuration and arrangement are
possible without departing from the spirit and scope of the present
invention as set forth in the appended claims. For example, the oven
controller 42 in a number of the embodiments described above is
responsive to one or more temperature sensors 80, 82 and/or position
sensors 79, 81, 83, 85 by changing the BTU output of one or more burners
60, 62 and/or by changing the speed of one or more fans 72, 74. In these
and other embodiments, the controller 42 can be responsive to an amount
of conveyor movement detected by one or more suitable sensors (e.g.,
rotary encoder(s), other optical or mechanical sensors positioned to
detect the amount of movement of the conveyor, and the like). In this
manner, such sensor(s) can send signals to the controller 42 to change
the BTU output of one or more burners 60, 62 and/or to change the speed
of one or more fans 72, 74 based upon the amount of movement of the
conveyor 22--and therefore the amount of movement of a pizza or other
food on the conveyor 22.